Explaining Science in the Classroom

_____________

F', EXPLAINING SCIENCE IN THE CLASSROOM U

O0 ni

Zz C Z

impressive book. It is an example of that rare item — a book complex scientific ideas, expressed in clear, simple language — about built on real teacher-learner conversations. Starting in the classroom, or the laboratory, with the most common occurrence — a teacher offering an explanation, it proceeds by analysing the nature of specific explanations so that teachers can gain fuller insights into what is happening. Having teased out the processes of explanation, the authors then reconstruct them showing how elaboration, transformation and demonstration can enhance the understanding of the learner. Professor Peter Mortimore

This

is an

—. —.

—S

m m

Is explaining science just an art, or can it be described, taught and learned? That is the question posed by this book. From extensive classroom observations, the authors give vivid descriptions of how teachers explain science to students, and provide their account with a sound theoretical basis.

Jon Ogborn, Gunther Kress,

Attention isgiven totheways inwhich needsforexplanationare generated, how the strange new entities of science — from genes to

Isabel Martins and Kieran McGiI licuddy

electrons are created through talk and action, how knowledge is transformed to become explainable, and how demonstrations link explanation and reality. Different styles of explanation are illustrated, from the 'teller of tales' to those who ask students to 'say it my way'.

U) (1)

0 0

Explaining Science in the Classroom is a new and exciting departure in science education. It brings together science educators and specialists in discourse and communication, to reach a new synthesis of ideas. The book offers science teachers very practical help and insight.

0

04

a.

_<

I I.!..

0

Jon Ogborn is Professor of Science Education. Responsible (with Paul Black) for Nuffield Advanced Physics, he has also done research on basic categories of thinking, on computer tools to develop reasoning, and on the learning and communicating of science. Gunther Kress is Professor of Education/English. He has written many books on language, visual and other non-verbal kinds of communication, and on the social nature of communication. Isabel Martins is a researcher in science education, interested in models of cognition and in the communication of science to lay audiences. Kieran McGillicuddy is a linguist and former high school teacher who is currently interested in the interrelationships of language, action and the meaning of things All four authors work at the Institute of Education, University of London.

S S

m

P CD

I 5

CD

CD

I

(f1

H[SDLQLQJVFLHQFHFODVVURRPLQGG

IsBN 0—335—19719—1

9

ftIID Ill

780335 197194

Explain ing Science in the Classroom

>

111111

EXPLAINING SCIENCE

IN THE CLASSROOM Jon Ogborn Gunther Kress Isabel Martins Kieran McGillicuddy

OPEN UNIVERSITY PRESS

Buckingham

Philadelphia

Suffolk Edmunds, St Bury Press, Edmundsbury St by Britain Great in Printed Kong Hong Ltd, Typesetters Graphicratt by Typeset

CIP

507'.12—dc2O 96—13433 1996 Q181.E87 Jon. Ogborn, I. Semiotics. 2. (Secondary) teaching and Science—Study 1. 0—335—19720—5 ISBN (pbk) 0—335—19719--i ISBN

index. and references bibliographical Includes cm. p. al.] [et

.

.

Ogborn. Jon / classroom the in science Explaining Data Cataloging-in-Publication Congress of Libraiy (pb)

1

19719 335 0

(hb)

5

19720 335 0 ISBN

Library British the from available is book this of record catalogue A 9HE. W1P London, Road, Court Tottenham 90 of Ltd Agency Licensing Copyright the from obtained be may reproduction) reprographic (for licences such of Details Limited. Agency Licensing Copyright the from licence a or publisher the of permission written prior the without otherwise, or recording photocopying, mechanical, electronic, means, any by or form any in transmitted, or system, retrieval a in stored reproduced, be may publication this of part no review, and criticism of purpose the for passages short of quotation the for Except reserved. rights All

1996 McGillicuddy Kieran and Martins Isabel Kress, Gunther Ogborn, Jon © Copyright 1996 Published First USA 19007, PA Bristol,

101 Suite Road, Frost 1900 and

1XW MK18

Buckingham Balimoor 22 Court Celtic Press University Open

CONTENTS

Preface Acknowledgements

Chapter 1 Classrooms, explaining and science Who are we?

What is there to understand about explaining science? Explaining: some examples Where do we come from? Our theoretical framework: an overview The structure of the book

Chapter 2 Opening up differences A difference of opinion What drives explanation? Creating interest 'What we're going to do next' What do you expect? Two main kinds of difference

Chapter 3 The construction of entities New things from old Making a new conceptual entity Why 'entities'? Resources for explanations Process entities

v viii 1 1

2 3

6 8 18

20 20 22 24 26 30 38 39 39 42 45 48 51

146 144 144 141 140 136 135 134 134

130 127 120 117 116 116 112 108 104 97 96 96 95 91 89

82 79 77 77

70 66 65 61

Index Sources

Context

sources and Context

Appendix

next? What claim? we do What Results Assumptions forward looking and Concluding

next? what and now, What

8

way' my it 'See way' my it 'Say tales' of teller 'The together' through it think 'Let's performances Integrating

explaining of 'Styles'

7

Chapter

Chapter

explained be to matter subject The interaction ongoing The teacher The structures Explanatory variation of Sources

explanation of Dynamics 6 Chapter again?' demonstration, is 'What action material and Meaning counterexpectation and Expectation matter with meaning-making metals: Alkali art by nature Vexing demonstration? is What

matter into meaning putting Demonstration:

5

metaphor and Analogy narratives and parables Stories, electrons with atoms up filling icebergs: Explanatory transposition Didactic transformed and made Knowledge constancy and Change knowledge Transforming explanations Prototypical parts their and Entities

54 52

knowledge Reworking

59 59 58 58

4

Chapter

Chapter

CONTENTS

iv

PREFACE

This book is one of the products of collaborative research between science education and semiotics and discourse analysis at the University of London Institute of Education. It is addressed to all those concerned with the teaching of science — to science teachers and to those who train or advise them. We started this work in the belief that science education had much to learn from those who study language, meaning and communication, an area which may be subsumed under the label 'semiotics' — the study of the making of meaning. We also hoped that the teaching of science would prove to be a fruitful field for investigation by semioticians, offering them new challenges and requiring new insights. In the event, we believe that both of these hopes have been realized, at least, they have for us. Not only has the collaboration led to the results described here, but it has also led us to further collaboration, currently on the use of images in science. And we will want to follow up the implications of the work which was started here. The book is based on video-tapes of a number of secondary school teachers explaining science. The argument of the book is copiously illustrated with transcripts taken from these recordings. This generates two problems of which

the reader should be made aware. One is that language — 'the words' — is thereby given prominence over other modes of communication, because there are no easy ways of representing all the non-verbal communication which is present. We have tried to offset this partially by including in the transcripts commentary on actions, gestures, writing, pointing and doing things with apparatus, etc. The second problem is that speech does not transcribe in any simple way into the normal forms of written language. Nothing, for example, corresponds in speech to the full stop in writing (just as nothing in writing

through- same the remain which pseudonyms, by identified are teachers The do'). 'I versus do' 'I example, (for ambiguity otherwise is there where stress, the indicate to type italic use we occasionally, Very characters. spaced with printed are out' 'spelt Words occurs. it where indicate to parentheses in notes added have but textually, this represent to tried not have We emphasis. particular thing some- giving when or dictating when used is intonation and pace special A letter. capital initial an without but words speaker's first the continue then and over, taken had speaker new a if as interruption the insert punctuation, final a without transcript speaker's first the off break we once, at talk they and another, interrupts person one Where letter. capital a with begins text speaker's each normally, taken are speak to turns Where elided. been has speaker a where tity iden- speaker's the for place the in and continues, speaker same the when text the in placed recording, the from elisions indicate .) (. dots Three units. intelligible less or more into text spoken the up break to as so placed but occur, they which at speech the in place the approximately at blackboardl), on writes [teacher example (for munication com- of acts non-linguistic describe brackets square in italics in Comments ?j'). [ a called is this 'So in (as utterance the complete would which answer an expects which utterance, an of end the at space tioning ques- hanging a — teachers by used often quite device a symbolizes ?j rhythms. habitual speaker's the of those than longer hesitation, or pause noticeable a indicates ] implied. or asked being is question A intonation. questioning a indicate 'OK?') (e.g. word a after or utterance an of end the at used (?), marks Question pause. audible an be will there times Some- repeated. or extended being is idea an because pause, actual no is there if even pause, a feels listener the where places indicate (,) Commas name). another to switches then but 'Henry' address to start might speaker a where 'Hen—' example, (for word uncompleted an for used also is dash A inserted. is aside an where or again, starts and something ing way one abandons speaker the where places indicate (—) Dashes expressof too. purpose this for used occasionally are semicolons and Colons possible. as sparingly as — speech represent to writing of conventions using is, that — this done have We read. to puzzling or tiresome be would them without speech the where speech, the of version 'written' a create to used are sentences new of letters initial capitalizing and (.) stops Full .

• •

•

•

•

•

•

•

•

•

•

•

transcripts: in conventions and notations following the used have We effort. minimum the with said was what of sense essential the grasp to reader the assist to language written of devices the of some used have we Thus read. to notations, linguistic in untrained teacher, science the for possible as easy as them make would which way a in transcripts the present to linguistics, in friends our annoying of risk the at decided, We finished'). I yet, me interrupt 'Don't says, which intonation the to corresponds

haven't

PREFACE

vi

PREFACE

vii

out the book. Thus the 'David' of Chapter 1 is the same 'David' who appears in Chapter 7, but his real name is not David. Students are also given pseudonyms where the teacher uses a name, and are identified by that pseudonym when they speak. Otherwise, student speakers are identified as 'Student', using 'Student 1', 'Student 2', etc. where it is necessary to keep track of who said what in a series of exchanges. We use 'Students' as identifying the speaker(s) when more than one student says the same thing. The pseudonyms preserve gender and ethnicity.

• Just occasionally, for our own purposes, we want to highlight a section of transcript. In this case, the relevant part of the transcript is set in bold italics.

We decided not to burden the main text of the book with references to other work. Instead, we offer at the end of the book an Appendix which lists

and briefly discusses the main sources on which we have drawn, putting them in context and adding references to further reading which may be of use.

We hope that this book represents a useful new departure in science education. In recent years, attention has been focused very strongly on students and their understandings of science and of the world around them. Learning science has been seen very largely as a problem for students, and especially so the more learning has been understood as an active process of the learner. We do not want to go back on that commitment to the need for learners to make knowledge their own, but we do want to open up a space for teachers to be thought about as having more to do than creating good conditions for learning. To teach is to act on other minds, which may then react as well as acting for themselves. So what teachers do in this way is worth describing and understanding. What we hope to have provided is the beginning of a new language for thinking about the act of explaining science in the classroom.

manuscript.

the of preparation the during help secretarial efficient and unstinting her for Benstead Judy thank We book. the of manuscript the on comments insightful many her for Frost Jenny and discussions, interesting for Dunlop Hugh data, his to access us giving for and discussions helpful for Christodoulou Nicolaos thank We Veel. Robert and O'Donnell Mick Leeuwen, van Theo by scripts manu- unpublished various in embodied ideas on gratefully drawn have We project. the through way part seminar two-day critical useful very a for us joined who universities other and own our from colleagues those thank We College. Technology City Harris and School High Riddlesdown School, Westminster North Girls, for School Swakeley's schools: their by given assistance the acknowledge gratefully also We them. with had we discussions helpful many the for and recorded, and observed be to themselves allow to willingness their for help, practical their for thanks our offer we Walker Rob and Vingoe Mike Thompson, Phillipa Fell, Will Richardson, Jenny Okolo, Ogugua McConlough, Eugene Marco, di Wendy Hogg, Ian Kirk, Shirley Gleeson, Chris Chandler, Bob To all. at sible pos- work this made who occasions, several on often recorded, lessons their have to agreed willingly so who teachers of group the course of was It acknowledge. gratefully hereby we which support R000234916; grant Council, Research Social and Economic the of support the with done was research The

ACKNOWLEDGEMENTS

Chapter 1 CLASSROOMS,

EXPLAINING AND SCIENCE

Who are we? book has been written by an unusual combination of people, coming from science education and from studies of communication. It seems obvious that this is a good collaboration to have if you are interested in how things are explained in the science classroom. There is, however, little tradition of bringing science education and studies of language together, even though independently people within science education have thought about language and people interested in communication and discourse have thought about science. Work starting from science education is in danger of using too limited a model of how language and communication works. And work starting from language is in danger of not grasping the sources of difficulty and the structuring of scientific ideas. We have tried not merely to add the two points of view together, but to make them interact, to reach a synthesis neither could achieve without the other. As a result, our notions of what it is to explain scientific ideas have changed, and so too have some of our thoughts about what is important in language and communication more generally. This book is one outcome. It is mainly addressed to those interested in problems of teaching science. But we hope it will also be of interest more widely, to anyone concerned with understanding language and communication. This

2

EXPLAINING SCIENCE IN THE CLASSROOM

What is there to understand about explaining science? Nearly every science teacher would agree that explaining things is fundamental to a science teacher's job. It is not of course the whole job, but it is a central and crucial part of it. Students whose teachers 'don't explain properly' get restive. And there is a lot of explaining to do. Why can metal ships float even though metals sink? How do we catch colds? What keeps the Moon going round the Earth? How does the fizz get into fizzy drinks? How do plants grow? What is the 'greenhouse effect' and does it matter? Where do the colours of soap bubbles come from? What happens to salt or sugar when they dissolve in water? What is rust and where does it come from? What are plastics made of? And so on, indefinitely. The pages of science teachers' journals, such as the School Science Review, are full of explanations. Many of them are in the form of demonstrations or experiments to do. The assumption is that if the teacher arranges for an effect to be clearly seen, it will be clearly understood. But we all know that this is not true. We show the atmosphere crushing a tin can as air is removed from it, but the class sees the vacuum pump 'sucking' the sides of the can together. We show an electric current going round a circuit and they see electricity used up to 'make' the light from a lamp. There are also theoretical things to explain. Teachers have to explain that it is the ceaseless motion of molecules which gives a gas its pressure, and

which accounts for the energy we call 'heat'. They have to explain that plants build their tissue using carbon dioxide, water and sunlight. They have to explain that chemical equilibrium is really a dynamic two-way process of change in both directions at once — that it only seems to be a case of nothing happening at all. Finally, and hardest of all, science teachers have to explain things that do not seem to need explaining at all. How do we see things? Why are our bodies warm? Why does coal burn? Why do hot things cool down? Why is the sky dark at night? Why do mammals have four limbs? Why are solids hard and liquids runny? Such things seem to common sense to be so obvi-

ous that there is no need to explain them. Indeed, nobody asks how to explain them because they are just the kind of thing we use to explain other things. Why shake the foundations unnecessarily? And yet it is typical of the sciences that they do shake the foundations of knowledge in this way.

The act and art of explaining to a class is much less discussed than the scientific ideas to be explained. Of course teachers swap ideas with one another, often about useful analogies and models. But explaining is not treated as something which could be understood, learned or taught. What can be said about it is mainly anecdotal, lacking any systematic or thought-out basis. Beginning teachers are supposed to learn by example how to explain, often without being conscious of doing so; experience is taken to be the only possible teacher. There is no body of evidence on which to base arguments about how explaining can be done, and what different ways there are of doing it. There is no shared theory of what is involved in explaining. Above all, there is no common language for talking about explaining, except for

CLASSROOMS, EXPLAINING AND SCIENCE

3

such common-sense terms as 'clear' or 'confusing', 'complicated' or 'simple'. We hope in this book to provide the beginnings of such a language to describe and compare different cases of explaining in the science classroom. And of course we hope that this language will prove useful to some teachers of subjects other than science. Our work has had two different kinds of outcome: practical and theoretical. The practical outcomes are ways of thinking about explaining very different topics and ideas in science — such as the periodic table and the nature of sound — which allow them to be compared or contrasted. Thus practising teachers get new tools for thinking about what they are doing. The theoretical outcomes are ways of linking the highly specific job of explaining scientific ideas to broader issues in communication. Explaining science can now be seen in a larger perspective, which takes on board how language, action, gesture and personal relations come together in acts of communication. But also, theories of communication are not left unchanged. In particular, they have to take account of the way science is not just about words but is also about things.

Explaining: some examples We will now briefly offer a few examples of explaining going on in the science classroom, to illustrate the kinds of things we found we needed to take into account. Here is a teacher (David) explaining the digestive system to a Year 10 class:

David: Now, the tube that goes through the middle of the worm, is [j The tube that goes through the middle of the worm is actually connected to the outside world. Here's the outside world here, here's the outside world here, and the tube going through the middle is part of the outside, of the outside world. It's not actually part of the worm, it's just a hole going through the middle. Let me put it to you another way. You know packs of Polo mints, yeah? You know if you buy a pack of Polo mints they look like this — and then you unwrap them, and you find that this Polo mint looks like this up to the top here, when you take the top Polo mint off and you eat it. But in the middle of the Polo mint there's a hole, yeah?, and if you've got a packet of Polo mints then that hole goes in and out the other end. Now — is the hole part of the Polo mint or not? The first thing to notice is that the words on the page are not enough. The teacher had a diagram on the blackboard which is an essential part of the explanation. Figure 1.1 shows more or less what it looked like, in all its stark simplicity. The diagram, and gestures involving it, are all part of the explanation. So is the imagined tube of Polo mints. The way David is making meanings goes well beyond language. Of course what he says is important, but spoken

language is just one of a number of meaning systems which are in use.

non-metals: and metals into table periodic the of division the of example for explanations, subsidiary many are there lessons, three previews which explanation, large-scale this Within logic. and sense common — sense of full it's because is easy it's why and subject, easy exceedingly an is chemistry Now really. else anything than easier much chemistry understand you help does — really it think I And wonder. a is think I table periodic the And Ruth: important: is table periodic the why explain to tries (Ruth) teacher a table periodic chemical the on lessons 10 Year of series a of start the near which in following, the is example Another once. at all scales time many on exist They analogy). mint Polo the contains example this (as explanations containing themselves often also whilst tions, explana- scale larger into fit they how seeing without understood be cannot classrooms science in Explanations whole. a as 'systems' digestive of account generalized more a into also and organisms, of variety a in works digestion how of account detailed more a into develop will It somewhere. going is it and somewhere from comes It isolated. not is explanation this Fifthly, work. our of theme major a form classroom, the within ideas of transformations and classroom, the in work which representations into ideas scientific of both transformations ways, various in knowledge of transformation the Indeed, analogy. and metaphor through ideas transform continually teachers science way the at look to necessary it found have We analogy. an as serve mints Polo the Fourthly, explanations. for need the create teachers science which in ways different the at looked has work our of Much explain. to something clearly is there result, a As seen. is what and said is what between created, deliberately tension, a is There difference. a such create to is earthworm an as picture a such to refer To — resolved. be to needing view of difference a of feeling a filled be to needing understanding of gap a up opening by works explanation the Thirdly, radically. sometimes transformed, be to have things explain, To obvious. and familiar seemed then until had what re-imagine to and unfamiliar, and new world the of parts make to explaining in need the — work our in theme constant another is This developed. being is objects topological as organisms about thinking of way new A strange. become able comfort- and familiar the making is David digestion. of geometry the of but earthworm an of not diagram, a is diagram strange The outside. the to open are insides digestive our that idea bizarre — bodies their about feelings day every- people's of view of point the from — but fundamental the towards ing work- is He all. at earthworms discussing really not is teacher this Indeed, earthworm. recognizable no like is here pictured earthworm the Secondly, essentials to reduced brutally earthworm An 1.1 Figure

CLASSROOM THE IN SCIENCE EXPLAINING

4

CLASSROOMS; EXPLAINING AND SCIENCE

5

Ruth: Metals always lose electrons and non-metals always gain electrons. So if you take Group I. . . going down they've all got one electron

in the outer shell and when they combine with another element they lose their electron and give it to another atom. Explanations exist right down to the smallest scale, for example of how to read the data in one cell of the periodic table: Ruth: . the bottom number tells you how many protons there are in the nucleus of the atom. What we have to look at are structures of explanations, not just individual bits of explanation. So far in these examples we have not heard from students. This is not to say that the students were not thinking, nor that the teacher was excluding them. The explaining going on was obviously highly tuned to their concerns and knowledge. David links his surprising view of digestion to something very familiar. Ruth uses the students' concern with learning being made easier to try to engage them in the work to come. Teacher and students talking together can also construct explanations. A common form of interaction, often described in other work such as John Sinclair and Malcolm Coulthard's Towards an Analysis of Discourse, is the .

.

triad 'question—answer—evaluation', as in the following example: Elaine:

Which of these things on the periodic table might be joined together to make hydrocarbons?

Student Hydrogen. Hydrogen and [ ?] Student: Carbon. Elaine: Carbon, right. These are compounds of hydrogen and carbon. Elaine:

Elaine clearly evaluates the response 'carbon'. She also evaluates the response

'hydrogen' by indicating that there is more to come, making this her next question.

In other cases, students make more of the running and are led into suggesting explanations (sometimes competing ones), drawing on what they know or can imagine. This is difficult to illustrate briefly, because it involves an extended to and fro of discussion. But here is a taste of one example, discussed further later in Chapter 7. The teacher, Leon, and his Year 10 class

are thinking about what might be needed in joints in the skeleton to stop the bones wearing away as the joint moves. Leon is in the middle of getting the class to 'design a joint': Leon:

Let's try and stop the wearing away. How can we stop the wearing away? Emma, how can we stop the wearing away?

Emma: Leon:

Emma: Leon: Student:

[Inaudiblel Yes?

Put a sheet of something between it. Yeah, what sort of sheet? Tissues.

explanations on either focus to tended has work previous But classrooms. ence

sci- in or explanations, in interest an express to first the course of not are We

from? come we do Where classroom. science the in explanation describing for developed have we framework theoretical the and relied, have we which on ideas the generally more discuss will we chapter this of remainder the In book. the of themes main the of several introduced have we examples, these With carbohydrates. or electrons genes, for same the say could We with. thinking for parts of kit biologist's the of part are They lesson). Leon's of subtext (a vertebrates of plans body of 'design' the to related and types, general of ber num- small a having category, biological a also are they But it. knows one ritis arth- gets one when and right, all exist 'Joints' reasons. particular for people particular by produced work cultural of result the — 'made' and meaningful are they time same the at But joints. in exists cartilage as world material the in existing there', 'out things certainly are things material These tions. explana- scientific in things material of importance the notice also We happening. it of evidence overt having always without imaginations, and ideas ledge, know- students' activate could explanations how about think to had have

we Thus tidily. so organized be really can elements chemical of variety and mess the whether wondered have may class Elaine's in and tubes, digestive just are really humans whether about silently puzzled have well may they class David's in But ideas. constructing in involved are students the Clearly

advert. car the in it show they like oil, Like oil? Like [gestures]. that doing be weight'd your moving, be weight'd your But oil. Like it. rubbing 'em stop They together] all [Talking

Student: Leon: Student: Leon: Student: Students:

Leon: though? do fluids would what of, sort Some yeah. fluids, like Fluids, Student:

they... but

Yeah, Student:

thing? plastic like, this, on rubbing they're other each on rubbing of instead So ?

Leon:

other. each hitting them stop It'd Student: on— rubbing of instead do, disc the would what And Leon: something. or disc a 'em, between sheet, flat a No, Student: band. elastic an Perhaps Student: know. I Student: [Inaudible] Student: Leon: it. isn't rough That's like, be that'd no, No, Student: CLASSROOM THE IN SCIENCE EXPLAINING

6

CLASSROOMS, EXPLAINING AND SCIENCE

7

as such (whether in science, or more generally as in Charles Antaki's book Analysing Everyday Explanation) or on language in the classroom.

It has been common to think of classroom talk in science as 'inducting students into scientific discourse' — as their learning to 'talk science'. We treat the same issues as a matter of how 'entities of science' are brought into being for students. This reflects our preference for going beyond the realm of words and what they refer to, to stress the role played by action, real and imagined, by and on material things. And we extend this preference to conceptual, meaning-carrying, semiotic 'things'. This view is inspired by some current philosophy of science, particular Rom Harré's Varieties of Realism and Roy Bhaskar's A Realist Theory of Science. We take from them the idea of explanation as resting on 'how things are', as being stories about how a set of entities can produce the phenomenon to be explained. This conception makes space for analogy and metaphor in explanation, often driven by implicit even unconscious metaphors. Here we draw on work such as Eleanor Rosch and Barbara Lloyd's Cognition and Categorization, and George Lakoff's book about the metaphorical basis of thinking, Women, Fire and Dangerous Things.

We also arrive here influenced by the later work of Jean Piaget on the construction of meaning through action. In his later work on the logic of meanings, Piaget offers an account of how the meanings of entities are constructed through action, through what they can do, what you can do to them and what they are made of (what parts they have). A valuable source, besides Piaget's earlier work, has been his posthumously published book with Rolando Garcia, Toward a Logic of Meaning.

Much discussion about problems in science teaching has revolved around the role of practical activity in the classroom — of 'doing and understanding'. Clive Sutton's more recent work on the language of science, in Words, Science and Learning, represents a well-articulated and richly illustrated argument for a necessary change of focus. His inspection of the 'language of science' from

the point of view of a science educator traces the metaphorical origin of scientific terms which are nowadays taken for granted ('cells' for example). He provides a plethora of examples of the way scientists' choice of words is part of their understanding and interpreting of phenomena. By choice he pays attention mainly just to words, wanting teachers to focus on them as active interpretations rather than as passive labels. At the larger scales of clause and of text, the linguists Michael Halliday and Jim Martin in their book Writing Science analyse the grammar of scientific discourse. They note how the strikingly 'dense' nature of scientific writing is achieved through what they call 'grammatical metaphor'. In this, a whole physical process is condensed into a single entity, for example, 'the bending of light as it enters a transparent material such as glass or water is called refraction'. A process becomes a noun, and the text typically goes on to talk about refraction and to use it in further relationships. Density quickly builds up, as in, 'Developments in hand may lead to variable-speed turbines and improved aerofoils that yield greater efficiency', to take an only modestly dense example. We see this, however, as much more than simply a question

entities constructing differences creating parts: main four with itself explanation, in meaning-making of account an • 'stories' to analogous as explanations scientific •

components: main three has — — our language framework theoretical Our describing for explanations them. elaborate and illustrate to is book whole the of purpose The ideas. these outlines merely section This done. be can explaining which in 'styles' different and knowledge, form trans- explanations how involves, explanation an constructing what needed, be to felt are they why and when are, explanations what about thinking of way a offer to is does it What ineffective. or effective is what 'bad', or 'good' is what you tell not does language This classroom. science the in explanations describing for language a is work our of outcome main The

overview an framework: theoretical Our earthworm. the of example the in above suggested as explanation, driving 'tension' or 'difference' semiotic of notion a on more rely we reason this For asymmetrical. more much surely is pupil and teacher between relation The joints). about above example the in (as part a play can and must this though knowledge, and experience pooling student and teacher through knowledge' 'common achieving being goal the of idea their about sure not also are We meanings. making of ways as — demonstrations doing experimenting, tables, and graphs pictures, gesture, talk, — classroom the of activity the all at look to and further, go to tried have We assumptions. and meanings shared of negotiation the at look rightly They 160). (p. communication' of part small a only are said, actually things messages, 'Overt — matters that everything means no by is classroom the in language the that clear been have ledge, Know- Common in Mercer Neil and Edwards Derek particularly Others,

them. with things doing and things on acting

through made being meaning much see we where science of case the in cially espe- language, to importance undue give may This words. between relations semantic grasping and patterns thematic identifying of one as explanations teacher's the understanding of job student's the sees Lemke Jay Science, ing Talk- his in example, For related. are they how and terms scientific learning as science learning seeing to leads naturally very point starting linguistic A evident. is action through constructed are meanings how about thinking our on Garcia and Piaget of work later the of influence the Here phenomenon. some for account to together acted have can things how about stories generating do, can they what and are things what on bottom at rely explanations scientific that instead argue We texts. scientific of genres different as 'explanation' and 'report' identified have Martin and Halliday world. the of views different and new building as it see We talking. of way special a just than more much — structure grammatical and writing of CLASSROOM THE IN SCIENCE EXPLAINING

8

CLASSROOMS, EXPLAINING AND SCIENCE

9

transforming knowledge

putting meaning into matter • variation and styles of explanation We now offer brief accounts of each; these will serve the reader as a guide to the book, and as a foretaste of what it has to offer.

Scientific explanation What makes a scientific explanation be something that explains? If I ask why it is raining and you tell me that water is falling from the sky, I have been told only what raining is. If you tell me that it is raining because it rains a lot in April, I have been told only that raining is usual and needs no further explanation. But a story about a depression coming across the Atlantic and bringing wet air with it begins to do the job. Such an explanation tells how something or other comes about. This makes a scientific explanation very

much like a story, even though it may not be told like a story. Some vital features of a story are that: • there is a cast of protagonists, each of which has its own capabilities which are what makes it what it is • members of this cast enact one of the many series of events of which they are capable

• these events have a consequence, which follows from the nature of the protagonists and the events they happened to enact Let us in this light consider some examples of scientific explanations:

• how a river came to be polluted • the origin of coal • the transmission of disease • the mechanism of heredity • how television works The explanation of how a river came to be polluted might be that farmers fertilize their crops, that rain washes fertilizer into the river, that the fertilizer makes plants in the water grow rapidly so that the water becomes full of decaying matter. The cast is farmers, fertilizers, rain, plants, etc. The story depends on knowing what fertilizers can do to plants, what rain can do to fertilizers, what plants do, and what rivers can do to decaying matter. Most of the things in the story are familiar. An explanation of the origin of coal also uses common knowledge, but the story extends over hundreds of millions of years; ancient tropical forests, the laying down of sediment over decayed vegetation, the effects of extreme pressure and temperature. It may involve subsidiary less common-sensical stories of continents drifting and rocks folding. The need for scales of time outside any possible experience demands imagination to think of the explanation as what 'really happened'. The existence of an explanation makes a difference to what counts as a phenomenon. A mountain range dividing two countries

they how and live they where know to want we exist, they If disease'. causes 'what as just of thought be to not are Germs story. one of world closed the beyond existing things, real as taken be to are protagonists their that insist contrast, by explanations, Scientific imaginatively. together fits everything which within world closed a create fictions best the of Some tales. ginative ima- like much not are explanations scientific respect important one In cause. some by moving kept be must object moving any 'obviously' sense, common everyday in today still and Newton before going; motion its keep to anything having without ever for Sun its around travelling on go must planet a that 'obvious' is it Newton since example, For things. other different quite by replaced be and obsolete become can obvious once were which things And point. the beside is day chilly a on rain the in out were you that infected; been have must you cold a have you If obvious. as treated are things unexpected some however, thinking, scientific Within are. things how is that When stops. explaining where is this And are. things how of because must they as out working events envisage we when obviousness of sense a have We of. made are they what and them, to done be can what do, can they what just is us, to meaning their things', of 'nature The do. to nature their in is it what doing things from arises happens what that so sense, makes it that so arbitrary; longer no is result the that so out work events how tells story A them. to done have or do to able be to supposed are involved entities the what know we until sense no make explanations Such sense. common everyday from far often are protagonists of worlds these that clear also is it But story. the up make behaviours possible whose protagonists of worlds of existence the on rely explanations scientific that clear is It mind. the of construction a of, thought just once someone which something clearly also are world, real the in existing as of talked Fields, home? to studio from travel thing a such could How particle.' a on act can force a which in space of region a is field 'A satisfying: than less seem answers the are, they what ask we when but bulletins, news the deliver they as enough real seem They fields. electric and magnetic — entities imagined new unfamiliar of realm the in again are we television of working the of explanation an With world. inaccessible an in things unfamiliar do which objects unfamiliar involves story The DNA. in sequences coded chemically of set a possessing becomes hair brown or eyes blue Possessing itself. of copies make can which DNA, molecule, a about story a into turns child their to characteristics passing father and mother A entities. novel of actions novel introduces heredity of mechanism the of explanation An directly. upon act or see to small too scale a on but world, everyday the as real as just world, a in belief involve them about tions explana- microscope, the in visible are bacteria Although viruses. and bacteria agents microscopic invisible of world new a with live we Pasteur, Since as. things see to what for; look to relevant is it what afresh us tells explanation The another. is crust Earth's the of piece rising currently a of case a as range mountain the thing; one is —

CLASSROOM THE IN SCIENCE EXPLAINING

10

CLASSROOMS, EXPLAINING AND SCIENCE

11

work. Taking something to be real means taking it to act as it does independently of our thinking and wishes. We cannot wish things into existence in

one context and out of existence in another, as it suits us. And as we get more confident of the reality of imagined entities, the more we can act on them or get them to act on other things. Scientific explanations also rely on formal, sometimes mathematical, constructions. Thus the protagonists in explanation-stories must also be thought of as including such entities as harmonic motion, rates of change, differential coefficients, exponential decay, negative feedback, vectors, and so on. It may seem artificial to treat these formal entities on a par with material entities. Are they not just part of the law-like patterns of behaviour of material

entities? The answer is that formal entities may begin life as law-like patterns, but often develop a life of their own in explanations. One example obvious to chemists is the case of 'orbitals' in atoms, treated in explanations of chemical bonding as entities with their own properties and powers, not merely as convenient pictures representing some arrangement of electrons. An 'ecological niche' is a formal metaphor used as if it were a real place to live, feed and be protected. Fields, once mathematical fictions, have become active real entities in their own right, storing energy and transmit-

ting information. In modern particle physics, they are perhaps more real even than matter, which in common-sense mood we take as the paradigm of the real.

Creating differences Nobody simply talks just for talking's sake, even if that is how it seems at times. Conversations seem to be merely casual, informal, inconsequential, usually pleasurable exchange; very little seems to be at issue. Certainly there should be no attempt to dominate. If this begins to happen, other participants feel uneasy and may comment on the shift from conversation: 'Don't start lecturing me!'; or 'I don't want to have an argument!'; or 'Don't be so serious!'

These responses indicate that even though they feel spontaneous and informal, conversations are circumscribed by rules — which become noticeable when they are broken. Rules of turn taking, topic change, interruption, or pausing while still holding the floor, have been extensively studied. Such rules are quite numerous, stable, and strictly observed by participants. Chil-

dren have to learn them, and until they do find it difficult to join in a conversation.

In our view, the fundamental motor of communication is that there is something known to one participant and not — or often assumed not to be known to another. I have something to say to you, which I think — or —

pretend — you do not know, and this allows me to open a conversation.

There is a difference between us. It may be a difference of knowledge or information. It may be a difference of interest — perhaps I want to inform you of, or recruit you to, my interest. It may be a difference of status and power, which I want to acknowledge by being polite to you, or which I

be to have meaning and nature whose pharmaceuticals to photons from entities new with it filling differently, world the sees It kind. in different totally often is it large; writ knowledge common just not is knowledge tific Scien- knowledge. everyday common and knowledge scientific established between that is account into taken be to needing difference more One crucial. remains need' they what 'want to students motivating But punishment. and reward of systems to examinations and curricula published from need they that decided been has it what accept to students obliging or encouraging of means of variety a provide systems education and Schools course. of teachers, to entirely left not is task This it. wanting into students coax or demand stimulate, provoke, to need may teacher the So know. to wants student the what and know to ought dent stu- the what between that difference: second a then is there But ference. dif- this bridge can teacher the that assumed is It know. to 'ought' student the what and knows student the what between that is difference essential one Thus schooling. of system the by but student the by not determined knowledge and knowledge needing as student the up sets school of context The different. very are roles the teaching, In initiative. the takes explainee the information; for request a from start generally explanations Everyday complementary. are relationships these course of And responsibility. and power of relationships their in is ference dif- crucial other The explainee. and explainer between knowledge in ence differ- a simply than more is explanation in issue at difference the Thus category. this into fall officers information and teachers explain: to job their be may It mistake. a for account to has one when as explain, to duty personal a have may They street. the in directions for asked is one when as explanation, for request a fulfil amiably may They plainees. ex- vis-à-vis motives of variety a have Explainers know. to needs or wants explainee the something knows explainer the knowledge; to related is issue at difference The explainee. and explainer namely fill, to participants for roles unequal and distinct have They conversations. from differ Explanations participation. of rights equal roughly have they that and equal, relatively as treated are participants that means This foreground. the in all are dimensions, pleasurable the affective, the social, the where communication of form that as of thought be may Conversation significant. particularly as participants by felt not is difference this but difference, is there then, conversation, In cause. its removes which effect an produces tension the poles, charged oppositely between arc an Like communication. towards drive a expectations, creates difference a of ence exist- The tension. semiotic of that is thing same the for metaphor Another communication. no is there difference, no is there where Conversely, communication. —

—

—

—

drives what is it, with dealing difference, of bridging The difference. this bridge to order in — briefly only if even — ensues communication and us; between problem no is there that know you let to simply or you, towards fondly feel I that know to you want may I feeling: of realm the in be may difference The me. to polite be to you obliging by you on impress to want CLASSROOM THE IN SCIENCE EXPLAINING

12

CLASSROOMS, EXPLAINING AND SCIENCE

13

learned. Everyday explanations are in terms of familiar entities doing familiar things. Scientific explanations are often in terms of unfamiliar entities doing unfamiliar things, and the student is a stranger in an unknown world. It follows that much explanation in science classrooms is not the explanation of phenomena, but is the explanation of resources the student needs in order to explain phenomena. Instead of explaining how sound travels, the teacher explains how to think about waves.

This also means that explanations between teacher and student in science are often shaped by what scientific explanations are available. When the teacher explains about sound being a wave or about chemical bonds being electrical in nature, the explanation forms, as it were, the tip of an iceberg. Unseen, underneath and keeping it afloat is a large hidden mass of scientific explanation. The student experiments with dissolving sugar in water; underneath lies all the science of solids and liquids, molecular theory and thermodynamics. It is this, unknown to the student, which gives point to putting sugar in water at different temperatures.

Constructing entities Everyday explanations generally fill in for someone a history of how things

happened, in a world of known protagonists. The fact that the train was delayed due to repairs to the rails explains the phenomenon of my being late. A loose tile in the roof may account for the ceiling being damp. Explana-

tions of this kind select from a cast of known protagonists and fill out a history which renders the thing to be explained obvious, natural, accountable. But very often, a scientific explanation needs to invoke protagonists which are not part of common knowledge. Explaining to someone then requires describing the possible protagonists as well as accounting for what they may have done. Indeed, the very phenomenon to be explained may not even be evident. We do not feel our muscles contract to make an arm flex; rather it feels that we flex the arm and thereby contract the muscle. Thus, we cannot ask what biochemical processes contract muscles; we do! Nor will a phenomenon seem in need of explanation if one has no idea that it could be explained. Most

people recognize that metals are shiny, but they do not think of this as explicable; it is part of what makes metals 'metals'. An explanation about electrons which are free to move, so that shininess is connected with the power to conduct electricity cannot be envisaged. Nor might many people think it sensible to ask why salt dissolves in water or wax melts in a flame. That is just what they do.

It follows that much of the work of explaining in science classrooms concerns the resources out of which explanations are later to be constructed. Protagonists have to be described, with what they can do and have done to them, before any story which explains a phenomenon can be told. Before we can explain how batteries light lamps we have to tell about electric currents, voltages and resistances. Before we can explain respiration we have to tell about lungs, blood, oxygen, carbon dioxide and haemoglobin. Before we can

discussion Every time. the all change students for exist they as Entities school. in transformed being continually also is it But context. school the reaches it before transformation much undergone thus has Knowledge knowledge. of transformation the for priorities new determining thus system, educational the in needs new erates gen- jobs, of demands and nature the altering by flow, This source. this from schooling, outside knowledge, of flow continual a is there Thus, another. is home every in electricity example; one are desk every almost on puters Com- artefacts. their through society into awareness technical and entific sci- and knowledge carry technology in developments time, same the At public. general the to and pupils school to undergraduates, to students, graduate to accessible made be to as so transformed being continually is knowledge Scientific school. left person that since made newly be will old years forty (say) reaches person a time the at around knowledge scientific crucial Much static. not is knowledge Scientific

knowledge Transforming explanations. future of construction the also is entities of struction con- the So explained. are which things not explanations, of part are which entities become to have They about. think to things only are they with start to if even thought, for tools become to have entities scientific Many crucial. is think' to which 'with versus think' to which 'about distinction The same. the much looks them using and constructing of work fundamental the but different, are They think. to which about or which with 'things' as way, similar a in discourse classroom and scientific into enter all they that is reason other The from. made are they what and them, with or to done be can what do, can they what from ing mean- get ones formal or abstract objects, real like Just meaning. of chunks new all are they that is reason One 'entities'? all them call we do Why itself. science in existence into brought be to had all once they course, of And, graphs). (straight-line structures formal or dulum), (pen- science of objects special freezing), or (melting processes gas), or (fluid classifications law), (Ohm's relations oscilloscope), (an instruments (atoms), objects minted newly but real be may They graph. sinusoidal a example for abstract, are Some table. periodic the example for patterns, are Some waves. or microbes example for intangible, or invisible are Some large. is students for existence into brought be to needing entities scientific of variety The explanation. unknown this just is present be to reason their but present, are they before given be cannot tion explana- The explanation. an in role coming their part in is exist to reason their because tricky, be can This students. for existence' into 'talked be to have explanations in used be to are which entities The explanations. for material the provide to has It defining. or labelling describing, like looks classrooms science in explaining of work the of much reasons, these For energy. and atoms, other and oxygen between bonding oxygen, about explain to have we burning explain CLASSROOM THE IN SCIENCE EXPLAINING

14

CLASSROOMS, EXPLAINING AND SCIENCE

15

gives an entity new possibilities and transforms its meaning — sometimes microscopically (I can use it here) and sometimes hugely (I didn't think it was alive!). The pupil's knowledge is constantly being transformed. An explanation does not 'transfer' an idea — it provides material on which to work to make an idea. These transforming processes were evidently at work in the classroom examples we gave previously. A worm was being transformed

into a tube; a joint was being transformed into a designed construction. One way to transform knowledge is to turn it into a narrative. Stories, whether that of the discovery of penicillin or of a personal experience — say finding food having gone bad — can act as effective 'knowledge carriers'. The

narrative relations in the story match the conceptual relations to be understood, and make them memorable and easily recoverable. The use of analogy and metaphor is crucial to the transformation of knowledge in the science classroom. Examples include the eye seen as a camera and the control of the hormone system by the pituitary gland seen as a conductor keeping an orchestra together. And, as Clive Sutton has eloquently pointed out in his Words, Science and Learning, large numbers of scientific terms rely on now dormant metaphor — oxygen the maker of acids, hydrogen the maker of water, alkalis the product of ash, lenses the shape of lentils, and so on indefinitely. We start from the view that analogy and metaphor are not an optional extra, not something which merely sugars the pill of literal meaning. We assume that metaphor and analogy are fundamental to language, to what is called literal meaning (and we note that in this sentence the words 'assume', 'metaphor', 'analogy', 'fundamental', 'language' and even 'literal' all have metaphorical roots — the last two from tongues and from writing). All meanings are made from other meanings, in the end being grounded in meaningful action in the world.

Putting meaning into matter Scientific theories purport to tell us 'how things really are'. Yet, looking around one, the world does not at all appear to be as scientific theories say it is. Energy seems to be lost, not kept the same all the time. Motion does not seem to go on for ever if there is no force. Sound is not obviously wavelike. Air does not seem to have weight. Scientific theories talk about a world behind appearances, and demonstrations try to bring that underlying world to the surface. Demonstrations in science teaching are designed to show the natural world behaving as theory says it does. But, as every science teacher knows, they easily 'go wrong'. What is concluded when they do? The failure is attributed to some interfering effect which spoilt what 'should have' been seen. In a sense, then, demonstrations cannot go wrong; the theory they exhibit is not put at risk. But a demonstration is still a confrontation of ideas — which may be what we please — with material reality which will not do just whatever we please. There is still some risk. Theories cannot say just anything we want.

We might say that the job of a demonstration is to get students to see things as theory says they are — that demonstrations are about 'seeing-as'.

we that outside air this in something There's thing. important very one forgotten you've fact actual In [] you— surprise might It OK? right. you are way No wrong. absolutely all You're Fifty.

Fifty. Daniel? Eighty-five. Eighty-five. Robert? More? Eighty. Eighty.

Susan: Susan: Daniel:

Susan: Robert: Susan: Darren:

Susan: Darren? seventy? on advances more Any cent. per Seventy Ricky: Susan: Ricky? cent. per Ninety cent. per Ninety Matthew: Matthew? I [ dioxide? carbon is cent per hundred that of much how guess anyone — out breathe you what of whiteboardl on 100% [writes cent per hundred a is out breathe you that gas the — out breathe you that air your If air? that in ] out breathe we dioxide carbon much how guess a have to like one Any- in. breathe you than more therefore Obviously dioxide. Susan: carbon contains out breathe you air the that prove can You

breath: exhaled in dioxide carbon detecting experiment an finished just has which class 9 Year her and (Susan) teacher a between exchange brief lowing fol- the example for Consider about. talking been have we aspects various the together brings explanation an so whole, one in all rhythm and melody line, vocal together brings which song, a Like way. particular a in trated orches- once, at all aspects these of all has explanation given any Rather, one. by one identifiable explanation, of kinds different describing been have we that suppose to mistake capital a be would it But compared. be can tions explana- which along dimensions of variety a described far so have We

explanations Orchestrating case. the is what and case the be to supposed is what between tension the of site interesting extraordinarily an therefore are Demonstrations it. about up make can we ideas meaningful what strains con- world material the of behaviour The imposed. be can meaning any not crucially, But, way'. special a in move things make 'I aloud, shouts almost track air An window. shop a or sign traffic a as meaning with loaded as is apparatus demonstration Thus possible. as close as is does it what and about thought be to is matter how of fit the that so crafted carefully be to has demonstration A matter. on meaning imposing as demonstrations at look to have we that means This 'being-as'. to 'seeing-as' from shift to shown, are they as are things that one persuade to is demonstration a of point The enough. quite not is this But cells. of made as seen be to is tissue particles; charged of flow a as seen be to is electrolysis wave; a as seen be to is Sound 16

CLASSROOM THE IN SCIENCE EXPLAINING

CLASSROOMS, EXPLAINING AND SCIENCE

17

hardly — we don't use at all. We take it in. [Gestures towards

mouth] We push it out. [Gestures away] Don't use it at all. Don't touch it. Don't use it. Don't react with it at all. What gas is that, Daniel? Daniel: Susan:

Nitrogen.

Well done, OK. Nitrogen is in the air out here, around me, OK? And over seventy per cent of the atmosphere around us here is nitrogen. It goes in. [Gestures towards face] It goes out. [Gestures towards face] It doesn't play any role at all. It might surprise you to know that only [pause, writes on whiteboard] four per cent of the air that we breathe out is carbon dioxide.

That's a very small amount. That indicator is a pretty good indicator. First, difference. By getting guesses which are wrong the teacher creates a difference of view; there is reason to explain. Second, constructing entities. At

least two entities are under construction, 'respiration' and 'the atmosphere'. Third, transformation. The natural process of breathing is being transformed into a biochemical affair of exchange of gases. Fourth, demonstration. Susan's gestures evoke an actual physical process of movement of gases.

There are, of course, many ways in which explanations can be orchestrated, and many aspects of difference, construction of entities and transformation which may be at issue. Thus we have to think about some of the sources of their variety and about some of the ways in which they can be put together. One source of variety is the context of surrounding explanations. Explanations hardly ever appear as isolated single events. They nest inside and fit alongside one another, to form larger patterns which are themselves explanations. Explaining the periodic table, or the behaviour of waves, may occupy many lessons. We cannot understand why what is being explained at a given moment is being explained unless we look at this larger picture. Similarly, many lessons have an overall explanation plan often clear only to the teacher — into which smaller acts of explaining —

intelligibly fit.

Another source of variety is the teacher. How a given teacher explains has a personal history — a history of experience and of relationships with pupils in the class. We cannot understand how a given teacher is explain-

ing something without having some idea of what resources of authority, knowledge, experience, materials, etc. this teacher commands. Only rarely does one see an explanation newly minted in the classroom. Mostly, teachers bring out well-practised forms; 'good' explanations are part of their stock in trade. Teachers are also careful to stimulate just those interactions with the class which they feel confident of managing with that class in that context.

Variety also arises from what is going on at that moment in interaction with students. The question a student asks may call for an explanation. The answer a student gives may need to be elaborated or corrected. Ideas which might be used to construct an explanation may need to be collected from the class. At other times, a way may have to be found to gain attention for

creating with deals 2 Chapter explanations. comparing and analysing for ies categor- of groups main three our analyse and up open 4 and 3 2, Chapters practice. in out work they how shows and them, justifies and elaborates book the of rest The book. the in found be to evidence and arguments the of view overall an give to attempted has chapter first This

book the of structure The right'. it 'get does ory the- the all after how show to try may Demonstrations theory. the plifying exem- as presented is reality excused; or ignored are seen is what in edges' 'Rough theory. certain a of view of point the from seen be 'should' they as evaporating, water or springs, down sent waves magnets, round filings iron as such phenomena, see to students get to try to out sets way' my it 'see style the using teacher The field. magnetic unseen an with filled as but empty as not example, for seen, be to has magnet a round space The way. certain a in things see to one require explanations scientific Many agent. causal active an as treated is 'energy' further', go it makes energy 'Its in example for — play to permitted are terms which roles grammatical the in implied often are Explanations ?]'). [ pitch the increases, frequency the ('If practised and out laid are words of forms Explanatory talking. of ways as on a my 'say call may we style A it explanations way' focus has obtained. been have which ideas official' 'making and reworking and contributions for opportunities up opening between fro and to continual requires It together'. through it think 'let's this call may We class. the from ideas reshaping and collecting through explanations at arrives teacher the which in that is style different very A form. narrative in put be readily can steel, of making the or continents of movement the disease, a by infection as such processes physical Some works. science how about explanations carry and resources stock teachers' of part are — penicillin of discovery chance the and Fleming urea, of synthesis accidental the and Wöhler dream, his and Kekulé apple, the and Newton — discovery scientific of stories classical The stories. of form the in 'carried' knowledge or given explanations of tales', of 'teller the of that is style such One styles. of variety a in together things these all put Teachers abstract? or concrete they Are processes? or objects they Are artificial? or natural they Are invisible? or visible they Are concerned: entities the of nature the on depend decisions These avoid. to what and assume to what explain, to what of made being continually are choices so difficulty, and kind in vary ideas Scientific explain. to how and what of choices on effect pervasive a has also hand in matter subject The encourages. or allows teacher the interaction of kinds what on depend will arise them of Which required. is explaining of kind what and done, is explaining how influence will arise, they before foreseeable not some interaction, of kinds these All on. so And restated. and recalled be to need may explanations given Previously explanation. complicated or lengthy a CLASSROOM THE IN SCIENCE EXPLAINING

18

CLASSROOMS, EXPLAINING AND SCIENCE

19

differences, with motivating explanations in a variety of ways. Chapter 3 discusses the construction of entities, both concrete and abstract, objectlike and process-like. Chapter 4 describes a number of kinds of transformation of knowledge, both in adapting it to school science and in transforming it as students learn. Chapter 5, starting from the role of demonstrations in explanation, shows how in science meanings and material things have to be brought together. Chapters 6 and 7 begin the synthesis as — having taken explanation apart we try to put it together again. Chapter 6 traces sources of variety in explanation, and Chapter 7 looks at a number of styles of explanation the teacher may use. Finally, Chapter 8 draws together the main ideas and points to issues, questions and problems which the work here has brought to light. —

No. No. development? sexual secondary through gone it has okay, right, born be to about foetus, little this little, this of think okay, — me tell to trying you are So [1 funny. It's it. about laugh Don't student] another [To true. be must It true. be must auntie, your Oh, auntie. My stunned] is teacher [The you. From from? Who heard. I what That's that. believe don't I heard. I what that's it, of shape The belly] rounded a [gestures where? the where, by, girl, or boy a having you're if or, a, or baby a having you're if tell can you that think you Do

Students: Student:

Leon: 5: Student 4: Student Leon: 3: Student 1:

Student

Leon: 3: Student 2: Student 1:

Student

Leon:

girls. are class 9 Year his in students the All purpose. on kind this of disagreement a provokes (Leon) teacher the follows, which extract the In differ'. to 'agree they course, of unless, — another one to ideas their explain to them for need a is there understandings, their in differ people When obvious. the with start us Let

opinion of difference

A

DIFFERENCES UP OPENING 2 Chapter

OPENING UP DIFFERENCES

Leon:

21

Okay, a little baby brother, a penis about this big, okay. [Teacher holds fingers close together in front of his eyes] [Student

laughter] True? True? You're telling me, that that alters, the swelling [Teacher makes a curved shape with his arms around his stomach] Student:

But you can tell if you're having a boy, like because your bump gets bigger, and if you're having a girl it's normal.

Leon:

Oh.

[Students laugh] Leon:

I would like to s—, I would like to see the paper in Nature, that established the — that data, yeah. Do you think its likely,

Aisha, that a penis on a little baby boy, is going to affect a pregnant mother's bump, in any way? Do you think it's likely? Student: Leon:

I'm not saying it's true or false. It might. You think it might?

Students: Student:

Yeah.

Leon:

Pardon?

It depends upon if the woman's having a girl or boy.

Student 1: Because, if she's having a girl, she gets uglier and fatter, and if it's a boy Student 2: No, no she doesn't. Student 1: That's what I've heard. Student 3: I heard this sir. Student 4: I heard different. Student 1: If, if it's a girl Leon: Uh-uh. Student: Leon:

[inaudible] Yeah?

Student 1: if it's a girl Leon: Yeah?

Student 1: it becomes round. The differences here look like differences between persons and what they believe or entertain to be the case. The persons are unequal in status: the teacher feels free to appeal to scientific authority. He produces an argument against the belief (the argument that a penis makes no appreciable difference to the size of a foetus). The students range against that argument 'what I have heard' or 'what I have been told', and they do not give up. After all, they know perfectly reputable adult people who hold and use this belief. Thus the difference becomes, not that between what Leon believes and what one student believes — a matter of a difference of opinion between two people — but a matter of a difference between cultures; between home and school, between the every-

day and 'science'. The argument turns from being about what teacher and student happen to believe to being about what students 'ought to believe'. We thus see that the difference behind the surface which motivates the discussion is a difference between what students know or believe at the

we and — scalpel fairy a and microscope special very a had we and it cut and it cut we and carbon of piece big a took we If Teacher: it. around field magnetic a have sumably pre- would it OK?, case, the is that that imagine to were we If Teacher:

'we'. of use the with shift that signalling often it, understand to attempt the in students Join to offer frequently teachers Science understood. be to ing need- world physical the — player another is there classroom science the in but, big a is it and But, backdrop. fundamental the is This things. different achieve to concerned are and things, different do to able are things, different know students and Teachers interest. and power knowledge, of difference: of kinds three all include these And student. and teacher between especially people, between differences are there classroom science the in Certainly interest. of power, of knowledge, of difference a be may It people. two between difference a as understood is 'difference' Often, above. mentioned 'distance' of idea the than generalized more but to close is metaphor The 1. Chapter in indicated we as 'difference', of metaphor the use communicate, people makes what for account to want who discourse, and communication in interested theorists Some generally. more discourse analyse who those of that with here work our link to and explanation, for need a create to order in do to has teacher a what at looking of ways gest sugto is into excursion small this for reason The twofold: metaphors grasp. my in now is elsewhere, once standing, under- An it'. have I 'now possession: of is metaphor related A gaps. across paths become Explanations it'. 'follow or it', 'see there', 'get can we stand, under- we When see'. to 'unable or follow', to 'unable being of standing, under- to 'blockage' a of stuck', 'being of speak We another'. to position one from 'moving of and apart' 'distance of is metaphor main other The communication. driving as force and conflict of one is image underlying The thought. of movement the 'smooth' to and explain to need a creating another, one on grating ideas different of — friction of that is metaphor nearby A it. relieving as explanations and sion ten- such creating as situations of and view, of points between 'opposition' or 'tension' of speak We differences'. our 'resolving of speak often We

explanation? drives What talk. better had they so agree, not do They people. two between difference a of there, still is which sense strong the is students, by intervention spontaneous and dispute of level high unusually its produces and alive, interaction classroom this keeps what Nevertheless, think. should they decided has someone what and now think students what between tom bot- at is difference the So school. in event an all after is this — change that of direction the decided has teacher The understandings. their changing at directed is It future. the in believe or know might they what and moment CLASSROOM THE IN SCIENCE EXPLAINING

22

OPENING UP DIFFERENCES

23

cut and cut and cut and cut - then eventually we would end up with millions and millions of these separate little bits of carbon, and they would be called atoms. And if we cut them any more, then they wouldn't be carbon any more.

What this kind of use of 'we' does is to blur the distinction between the human participants, and to encourage a focus on what is being talked about. Of course, the use of 'we' is a symptom, not a cause. It arises when the teacher has done work to create a social situation of acting together to learn, of joint agency. This is done in many ways, small and large. One small one is completing a thought together:

Teacher: Microbes, and you need a micro [ Students:

scope [Teacher says it tool

Teacher:

to see them.

?l

A much larger one is the example with which we began this chapter, of teacher and students arguing together. Another is the teacher 'thinking aloud', with hesitations, false starts and re-attempts. This may be an attempt to explain, or — more involving still — it may be creating something for students to think about, as below: Leon:

. then what — what do you see? What do you actually see?. . is that what — remember when we saw — I drew the one with three beams of light coming in — what happened to that? Did it go out? Did it — did it actually refract outwards? Did it? Because — look — we said — we said that this part — this part at this end was .

.

.

just like a bit of a prism, OK? So if light came in — if light came into that part — imagine that's a prism there, right?, where does it refract to?

The hesitations, rephrasings and repetitions here are not, in our opinion, 'lack of clarity'. They signal that here we have 'thinking in progress', and so that there is something really to be thought about. By contrast, a question like, 'What happens when a light ray strikes a lens here?', signals something very different: 'what you ought to know', and locates the difference back between teacher and student, not between the student and the phenomenon to be understood. We want to say, then, that explanations in the science classroom are mainly driven by differences between what students know now and what they need to know. For this reason teachers often talk in the tense of 'We are going to . .': the future in the present. Part of the job of the teacher is to open up, to create, this difference. Of course, merely being in school tells the student that some such difference will be at issue one is supposed to be there to learn. But — and in science this creates a lot of work for the teacher — it is often not easy for the student to see in advance just what difference in understanding needs to be bridged. .

—

your to happened what see and hole, this through look thr— look a have just I'll and again, and now breakfasts free have just know you and days few a for here stay just you don't why don't why 'Look, said, he bloke, this to said he so right, That's David: see. could he and Oh, Student: digested.' being it's while food the to happening what's see and hole that through look could means this minute, a 'Wait thought, doctor the suddenly —

— —

I

digestion: of process the study to opportunity the used doctor whose and wound, gunshot a by opened was stomach whose Martin St. Alexis trapper fur French-Canadian a surrounding events extraordinary the concerning lesson a from example an note us let moment, the For 7. and 4 Chapters in this about say to more have We story-telling. through is interest sustaining of way obvious One physicists. for interest passionate their acknowledging whilst uninteresting, supremely the of prototypes as stand might gravity, under motion analyse to how tion men- to not pendulum, a of oscillation of period the determines what of question The appealing. more them making of hope in uses practical their to linked be may both though fascinating, obviously less is solution a of acidity the measure or sulphate copper electrolyse to How move. fact in do they that fact surprising the told been have students once case, a hard too not is continents of movement the Perhaps students. to concern less much of matters other many in interest creating of task the face teachers Science

reproduce? do they do How Katie. idiot, an such be Don't Student: Katie: rats? female get you Can testes. its are Here David: ten [Laugh David: [Laughter]

words. correct the use well as might We

penis. its is That David: willy? his that Is Student: saying was I as Right, wait. and down sit Just time. a at question one have let's on, wait on, Wait David: that? causes what constipated, you're when happens What Student: its that's and rat, male a is this tail, its underneath It's David: that? What's Student: David. is teacher The 10. Year from below example the in as sexual, especially functions, bodily — so more even — and issues environmental include interest of areas Common notably. increases ask they questions of variety and number the are they when and things, some in interested 'naturally' are Students obvious. the to return us Let

interest Creating CLASSROOM THE IN SCIENCE EXPLAINING

24

OPENING UP DIFFERENCES

25

breakfast as you're eating it?' So they did this, and the doctor wrote these great long diaries of what was happening, he took bits of — he took bits of boiled egg, for example, and tied the bit of boiled egg onto a bit of string, stuck it through the hole, and then he st— took the time, 'Eight o'clock', 'ni—', you know, 'nine o'clock', stuck a boiled egg through [mimes waiting] 'five past nine', pulled it out, had a look, to see what was happening, wrote down what was happening, stuck it back in. And he did this for day after day after day, with all sorts of different foods, sticking it through the hole, pulling it out, looking to see what was going on. . . Anyway, that's how they discovered what was happening inside the stomach.

The whole bizarre story can be found in Chapter 7. Beyond its immediate (and perhaps dubious) appeal, the story serves other interests. Its force comes in part from the special collision between eating as everyday experience ('have

free breakfasts now and again') and the biological interest in digestion as a biochemical process ('I'll just have a look. . . and see what happened'). The continued oscillation between the two worlds of personal well-being and of 'scientific observation' is striking, and gives the tale its ghoulish character. It offers a definite — and not wholly sympathetic — image of the kinds of interest science has in things. We will begin Chapter 3 with a similar example, but there seen from the point of view of transforming the objects of concern — of seeing them differently. This example leads us to broaden the notion of 'interest' somewhat, beyond 'natural curiosity' or 'entertainment'. Teachers cannot, and in our data do not, try to make everything attention grabbing. This is simply because much of what is of interest to the sciences is not of immediate fascination

to students and cannot be made so without deforming it. What is a matter of interest, of concern, what is a problem, varies from one culture to another. The cultures with which we are concerned are those of the everyday (in our case Western industrial) world, and of science — and specifically

science in school. Quite generally, but very importantly in this particular case, cultures decide what it is important to attend to. Culture decides what counts as problematic. 'Interest' now becomes, not what one finds appealing, but one's main concerns; what one is trying to achieve (as in the sense

of the phrase 'an interested party'). And the problem is that the sciences have their very special interests which are not necessarily shared with others.

Understanding the motion of things like pendulums is one of them, for reasons not to do with pendulums but to do with much larger issues, namely understanding the causes of motion throughout the universe. The teacher's task is to reproduce some such structure of interests in students, if possible. That is what it would mean to make them 'more scientific'; it would be to make them ask the kinds of question central to the interests of the sciences. And this is no small matter: to change one's interests is to become a different kind of person who belongs in a different culture.

Much of the remainder of the chapter concerns how teachers set about

growing...

.

.

Health. Student:

that? about explicit more bit a be you Can things. Growing got. you've that ideas the of some up put just Let's down. this write Don't Okay. things. Growing things. growing Yes? organic? word the From include? might topic this what ideas any got — have? Anyone .

.

Elaine:

,

Elaine:

questions. next her to responses the in shows difficulty that and heading, a such of students to meaning of lack the of aware well is Elaine please? heading main your as that put you can So chemistry'. 'organic called it's and topic, new a is today on start to going we're What Right. Elaine:

that. simply doing than cern con- deeper much a has she fact in that however see will We have. already they which associations and ideas from starting by interest students' 11 Year co-opting (Elaine) teacher the shows example next the surface, the On 'density'. of meaning the concerning 3, Chapter in example another give We ideas. new of set a with simply started get to hard it makes which meanings of interlocking this is It others. the from meaning its gets element Each anything. understand can one before understand to lot a is there case elementary this in Even 'circumference'. and 'diameter' 'radius', like terms and perspective), student's the from be, may they (whatever curves plane ing includ- others, with interlocks interest This circles. in interest of kind unusual very a has culture mathematical the that plain too all is it And circles. about think mathematicians geometry, in how, you showing is It is. circle a what you telling not is text The peculiar. more even look may it does, one if And out. find to way the be not would this was circle a what know not did one If 72) 1993: Martin and Halliday in (quoted circumference. its called is circle the of length The radius. the twice is circle the of diameter The circle. the of radius the called is distance This centre. the called point particular a from distance same the at is it on point every that property special the with curve plane a is circle A Science: Writing Martin's and Halliday in definitions of discussion a from taken textbook, 6 Year a from example an with this illustrate We incomprehensible. less or more are learned be to ideas new the of meanings the of statements brief so: doing in difficulty crucial but simple a is There understood. been has topic new the of much anything before topic, new a of nature the explain to need frequently teachers Science

next' do to going we're 'What

in

—

sense social wider our in interest

—

explanations. scientific interest of structures new creating

CLASSROOM THE IN SCIENCE EXPLAINING

26

OPENING UP DIFFERENCES

27

Sorry. Health. Natural. Okay. Healthy. Put some hands up — the word organic — what does it mean? Student: [Inaudiblej Elaine: Sorry? Crops Elaine:

Sorry — somebody

Elaine:

said? Shampoo. Right.

[Murmurs of surprise and amusement]

Fine. Any other ways you've met this word organic?

Elaine:

Student: Food. Elaine: Food. Right.

As this interaction continues, Elaine can bring out that the main associations of the word 'organic' are with living things. She does so because she is going to spring a surprise. The surprise is that 'organic chemistry' is not

the chemistry of living things, but is just the chemistry of carbon compounds, and that this includes the chemistry of living things, but much else besides including such non-natural substances as plastics. So this introduction, easily mistaken for a case of 'eliciting what students know', is going to be used to undermine what they know. The 'organic', the 'natural', are to become not what they seemed. And Elaine will do this through telling the story of the accidental synthesis of urea — an 'organic' substance made from inorganic materials at a time when this was thought impossible because 'organic' substances were held to need some special contribution from living organisms: Elaine:

.

.

. they thought that these special chemicals could only be made

inside living things or they were the waste products of living things or the decayed products of living things. In fact, they had a theory called the Vital Force Theory. More of this episode can be found in Chapter 4. Here our concern with it is the way it confronts the clash of meanings and the differences in interest between science and everyday life. To do organic chemistry is to ask a completely new set of questions; no longer questions like, 'Is this substance good for you?', but questions like, 'How many carbon atoms do the molecules of this substance contain?'. Elaine's job has been both to expose this difference, and through interaction with the class and some history of chemistry, to try to bridge it. The work she is doing opens up two complementary differences:

firstly that between the student now and the student later, after learning organic chemistry, and secondly, that between the interests of and questions proper to two different kinds of knowledge about living materials — the scientific and the everyday.

Utility

A common strategy in introducing a new topic is to stress its usefulness. Indeed Elaine, in her introduction to organic chemistry just discussed, deploys this strategy too:

digestion: on lesson David's in instance, For utility. to appeals briefer and simpler of examples many course, of are, There it. learning of business the with and it, from available is knowledge what with like, is chemistry what with do to differences issue: at be will which ference dif- of kinds several establishing is time, of space short a quite in doing, also is she what But possible. as facets many as to appealing by come, to is what reject to students for possible as difficult as it make to trying is Elaine if as seems certainly It overkill. motivational to close as earlier, discussed duction intro- the of part the with together taken this, all see perhaps might One together'. teacher and students as 'we to then and chemists' as 'we to people' interested ordinary as 'we being from shifts passage this in 'we' the Correspondingly, students. as job their of facility the in change a and chemistry, to proper interests the towards in interested are they what in change a them, interest already that things of knowledge in change a become: might they as and now are they as students between difference of kinds three creates she differently, it put to Or, learners. as concerns their to also but novelty, technical in and things living in interests 'natural' pected ex- students' to appeals she Thus learn. to easier it make to knowledge of organization of (iii) and materials useful and new making for (ii) biology, ing understand- for (i) utility are They 'usefulness'. of kinds three evokes Elaine learn. to us for easier much it make to going is which packages little discrete into compounds carbon different these about knowledge our organize can we So group. the of members other the all about guesses good pretty some make can you then group, the of member one about learn to have only really you so common in lot a quite have they group a Within groups. into put be can about learn to have do we that those and them of all about learn to have don't we is news good the but news, bad the was that now Right, on. so and furniture for foams polyurethane our tiles, ceiling styrene poly- our terylene, nylons, our clothes, our for fibres, thetic syn- our all now, granted for them take just we And around. weren't ago, so or years 100 that things the dyestuffs, plastics, like now granted for take we that things the producing for istry chem- the also It's that. like things and proteins and hydrates carbo- of chemistry the biology, about talking we're when use we that chemistry the it's because chemistry of part ant import- extremely an It's together. put elements other the all as compounds many as times eight or seven about forms Carbon Elaine:

compounds. carbon different million half a and three about are there — chemistry organic about reading was I time last the but — now by this on date of out be could I and about, are there — news bad The Elaine: bad. The Student: news? bad the or news, good the want you do Now, Elaine: CLASSROOM THE IN SCIENCE EXPLAINING

28

OPENING UP DIFFERENCES

29

. but I've forgotten to tell you about hiccoughs, and you all want to know how you get hiccoughs don't you?

David:

. .

Promises and anticipations A good many science lessons start by naming the topic to come, and this may include some kind of definition of what it is about. We are interested in the function of such a step, so far as later explanations are concerned, over and above having a heading written in students' exercise books. Here is the start of one Year 10 lesson: Tom:

OK, the alkali metals. []So what — would you start off by doing

[] is copying those first three into your book. Copy the three boxes into your book. It may be bigger. Student: Sodium. Tom:

Lithium, sodium, potassium.

The teacher is going to do a demonstration (see Chapter 5 for an extended account of this lesson) to show the similarities and differences between the three elements, the nature of which leads to their being called 'alkali metals'. This and other such groupings of elements will be crucial to much later learning of chemistry; indeed it is very common to use this group of elements to introduce the very idea of such groups. One might argue that it would be better if the label 'alkali metals' were to come at the end, when some reason for choosing it had been provided. As it is, it is no less 'incomprehensible' than the circle was previously. The name comes before the basis for the name. This argument, however, is to mistake the function of this kind of action of a teacher. The title is best understood as making a promise. It names something not yet known and promises that it can and will be understood. A difference is opened up between where students are now and where they will be, in the shape of a blank but labelled conceptual space. Interestingly, the form of the lesson to come actually implicitly follows this metaphor, 'filling the space' item by item with a comparative table of the properties of the three elements. Providing for that exercise is indeed the reason for the initial activity of copying boxes to be filled in. Near the beginning of Chapter 3 we give an example in which a definition (of 'density') also functions as a promise of understanding to come — an interesting case since definitions are usually envisaged (wrongly in our view) as clarifications, not as things identifying the 'not yet understood'. The definition of a circle, discussed above, must function in the same kind of way. Here are some further examples of talk near the start of explanatory episodes which are also, in the above sense, not yet strictly comprehensible, but

which serve to promise an understanding, and so once again open up a difference between students' present and anticipated knowledge: Teacher:

.

.

. electricity

and magnetism are two things which are very

closely related, OK?

student: 8 Year one for salient is what is Here eye. the about anything knows who asked has Alan, teacher, The phenomenon. intuitive counter- a to attention draws who student a is it example, next the In basis. and authority respective their and knowing of worlds two between that created; is ference dif- important and large A it. believe students the by trusted and to known people reasonable why to as remains still issue the accepted, is idea the of rejection biological teacher's the if Even understanding. further with bridged be to gap a or resolved, be to tension a creates clearly It another. with phenomena about beliefs or expectations of set one confronting of case a is 'bump', the of shape the from sex baby's the tell could women pregnant whether about discussion a of chapter, this began we which with example The

Counterexpectation others. some in fill then and two, these illustrate we First right. is it if out finding before answer an to themselves commit to them getting to phenomena prising sur- see students letting from ranging sense, broad a in 'expectations' term the use We explain. to need a produce can which difference a creating of way main another as expectations, students' on draw constantly Teachers

expect? you do What sense. make utterances the make will which come to work of harbingers a as utterances such understand to learn They students. for lem prob- a necessarily not is it And strategy. a as it of aware be not may teachers though strategy, common quite a is It statements. such producing in 'mistake' of sort any making is teacher the that suggest to want we do way no In name. baptismal a solemn so deserve or interesting way any in be should it why at hinting without is pendulum a what you tells last the And table'? periodic the to relation 'in be, that could what but particles', of 'drawing the promises third The mean. could work' graphs 'how what or experiment, an in computer a use to is it what out finds one when sense much make only will second The magnetism. electro- of nothing knows who someone to mysterious quite be may first The

swings. which end the on hanging something and string of piece a is pendulum a in is there All thing. simple very a basically is pendulum a Now, Teacher: table. periodic the to relation in particles drawing at look to going we're you. for table periodic the summarize to going I'm Teacher: measurements. scientific make can which here things two got I've work. graphs how better understand will you lesson the of end the by hope also I graph. a make to going is it and experiment, an in used be can computer a how see will you Teacher: .

.

.

.

.

.

.

CLASSROOM THE IN SCIENCE EXPLAINING

30

OPENING UP DIFFERENCES

31

Student: When you [I the pictures in your eye [lit doesn't come straight away like the right way round — it it comes upside down. Alan: Good. Good. So the image that's formed in our eye might actually be upside down. —

The issue is not forgotten. At the end of the lesson Alan returns to it: Alan: The image gets picked up by the light-sensitive cells in the retina, and messages are sent to the brain, and it's actually the brain that

effectively turns that image the right way round so that we see things the right way up. If this addresses the difference created by puzzling about how upside-down gets to be experienced as right-way up, it does so only partially. It opens up yet further queries, notably how a brain could possibly do such a thing. And that this is so is signalled by the use of 'effectively', indicating that there are mysterious depths here which it is not now proposed to plumb. Chapter 1 contains another example of counterexpectation, when a teacher shows a class that they have all grossly overestimated the amount of carbon dioxide in exhaled breath.

'I wonder if I'm right?' Although science teachers often ask questions and nominate or allow one student to answer — often to the relief of those passed over — they sometimes get a whole class to commit themselves to an answer, so raising the tension at least a little. Early in a lesson on joints in the skeleton the teacher (Leon) gave out statements to judge true or false. He insists on a clear answer:

Leon: 'Bone is not a living tissue.' Is that true or false? I don't want you

doing one of those 't's where you can change it into an 'f'. Soon he and the Year 10 class come to the answers to this question: Leon: Next question? Student: Bone is not a living tissue. Leon: True or false, bone is not a living tissue. False, it's most definitely, Student: It's the first question I got right. [Student laughter] Leon:

It's a living tissue. Why do some people think of bone as not living? It's a psychological thing.

I, well what I believe about this is, whenever do you actually see it? Student: You don't. Student: Cut yourself. Leon: No, when do you actually normally see bone? Student 5: When you Leon:

no.

—

Alan: afraid I'm year, this Not that? do we Can Student: Ugh! Students: Alan:

inside? look a had and up eye an cut ever anybody Has

eye: the about lesson 8 Year a in used, much not but created difference a of example following the Consider created. been has that difference the sense They questions. spontaneous posing start themselves students that is happened has this that sign A things. unusual or surprising about thinking or seeing by created be can Meaning-tension

that!' "Imagine resolved. be to tensions creating or meanings new with filled be to space making challenged, or used either are tions expecta- students' which in examples other of variety a to now turn We rarely. quite it saw we certainly — lessons science in underused probably is It everyone. amongst difference distributing of way a is issue, an discussing before position a to commit to students all getting of device, This opposite. the think might one why of and material living is bone why of explanations drive helped and created was difference A out. turn would it how in ested inter- were and be, might answer the what of expectation some formed had students The answer. an to student each of commitment prior the to thing some- owe must issue that of existence into bringing The exchanges. lively these in clear very is — resolve to difference a — issue an of existence The alive. absolutely it's body, your of bit dead a like not it's totally, living, it's grows, it and living, actually it's stuff, living it's mu—, it So you? can't grafts bone do can you Bone, Bone.

?]

[

marrow. Bone marrow. Bone people other into them put and ?] [ people

Leon:

Student: Students: Student:

Leon:

living? bone that is skeleton the see actually you when thing, one get let's Okay,

Student: Student:

some from take actually you can what Because yeah? alive, much very is bone, But stuff. dead like, it, of think you so, ground. the in they're Because like like, looks just yeah, stuff, compounds, mineral like of sort some like, them of think you and skeletons, see you know, you s—, you what on, based is bone, about think people some what so see, You No. No.

Leon:

Student:

Leon:

laughter] [Student

obviously. skeleton that out bring you when or Yep, 5: Student yourself. cut 5: Student you When 1: Student 32

CLASSROOM THE IN SCIENCE EXPLAINING

OPENING UP DIFFERENCES

33

The work in fact then turns to looking at pictures of the construction of the eye. There is no doubt that the idea of dissecting an eye produces feelings of revulsion in many people. As in previous examples, a difference — indeed a gulf — opens up between the human feeling for our eyes and our sight as precious possessions, and the objectifying mode of biological investigation of their structure. This difference is here neither used nor explored, fertile

though that might have been. But evidence that the tension remains is provided by a number of questions students raise later in the same lesson, after Alan mentions the matter again: . if at some stage in the future you see a demonstration of an eye being cut open

Alan:

.

.

Students: Ugh! Alan: and actually take the lens out, and you can have a look at this

lens [ ] you'll see chatter] Alan:

You will see

Student: What year will we do that in, sir? Alan: You might do it in GCSE. Student: When you've taken the eye out, does the pupil still work? It won't respond then — the eye will effectively be dead.

Alan:

Is it true that if you push there at your eye you can take your eye out? Student: Oh don't! Alan: I very much doubt it. I wouldn't try. Student:

Has this to do with expectations, as opposed to just being 'natural' feelings of revulsion? We think so. It has to do with the meaning of our eyes to us, and so with how we expect to feel when dissecting them, contrasted with how we are being expected to feel the latter signalled by the objectifying language used by the teacher. The gulf between the two worlds is, however, not always so great in this lesson. At another point, Alan is talking about the action of the pupil of the eye: —

Alan:

So if it is quite dim — if there isn't very much light around —

your pupils have to open to allow as much light in as possible. What might happen if it was very very bright and then

our pupils were wide open? Student: They'd get small again. Student: They'd get damaged.

You could possibly damage your eyes. . there'd possibly be too much light for them to respond to — so the pupil closes down again to limit the amount of light. Student: How can you? — If your eyes are open and it gets? — How can it control it? Alan: Oh you don't do it consciously. It all happens for you. Alan:

.

helmets. the in glass The Student:

through? travel to have sound the did what So Glen, hear could Neila — other each hear could they touched helmets the when that is there assumption the So Glen? reach to through travel to have voice Neila's did what touched, helmets the when that say they 3, Question at look a have we If moment. a in that at look a have We'll it? Is it? Is

Alan:

it?

isn't through, getting from it stopping

is wearing

they're What Student:

space? in air no there's that it Is Student: yes? word, a hear can't Neila 'Whaa!'. go, Glen see can You picture. first the is This shouting? was he if even Glen hear Neila couldn't why saying, is 2 Question then, Now Glen. naut astro- other the called they've and Neila astronauts the of one called They've pictures. those on astronauts two are there space: in another one to talk could astronauts two whether about question textbook a uses Alan sound, about lesson a In facts. surprising potentially of sense making involve often can about think to Problems happen. to expect to what about thinking are really students the that suggests this All on). turned light the and up woken (being example good a offers spontaneously quite Another willed. being without happens thing a such how pupils; the controls what know to wants student one Thus thinking. own students' the from come They know. they what illustrate to 'examples' just not are these And used. being is but challenged, being not is expect and know students what Here it? doesn't readjust, to eyes your for time of period short very a just takes it And up. eyes your cover to got you've eyes] his 'uh!' go you and light the on switches in [covers that like walks somebody and. possible as in light that of much as get to open wide are pupils your so that like anything or shadows any out make to struggle to have really eyes your that around light little so there's eyes Your something. see to struggling you're and room darkened a in there lying you're - morning Alan: the in up woken you've So it. of example brilliant yeah OK, —

—

. .

—

—

—

—

—

.

.

—

Yeah. Student:

in comes mum your when on comes just light the and bed in you're When Student: OK. away, straight up close to starts pupil The it. about think to have don't You respond. automatically would they but wide, too be might they moment brief a For respond. automatically would eyes your is happen would what But Alan: —

—

open. wide are eyes your if it about anything do can't you though damaged get still You Student: 34

CLASSROOM THE IN SCIENCE EXPLAINING

OPENING UP DIFFERENCES

35

We must notice here that the (Year 8) students are not accounting theoretically for what they know to happen, but are asked to work out what 'must' happen from what they know theoretically. Theory is driving 'fact'. What one should expect is the driving idea, and what happens is going to be made to fit. The reason, of course, is that the lesson is about the theory, not about the phenomena. A later passage in which theoretical results are 'inferred' from fantasy facts helps make it clear that this is what is going on:

Alan: Well the fact that if they had some new radios they could hear each other — so what would that prove to us that radio waves can do?. . . OK so the radio waves that are going between their radios must be able to travel through space. There are thus two different kinds of 'imagining strange things'. One is seeing something strange and not easily explicable, such as an upside-down —

image, a ball supported on a jet of air, a big spark from a small battery — and so on. The phenomenon is unexpected and the issue is one of explaining it. The other is hearing one of the stranger explanatory stories of science, such as motion going on for ever, light travelling through nothing, or the unfolding of a new organism from a single egg. Now the problem is one of coming

to terms with the odd behaviour of the entities in that story, and of believing that the phenomena it suggests actually happen (can astronauts not hear through space? does the stretching of time in relativity really happen?).

'What do we think now?' We must avoid giving the impression that creating differences, motivating explanation, is something to be done at the beginning of some explanatory episode — to get things going — and to be abandoned afterwards, as the nowwanted explanation unfuris. On the contrary, it happens continuously. As bits of explaining get done, students have to thiqk what each means, and whether there are gaps yet to be bridged or tensions to be resolved. 'Does that mean that if. ?' questions from students are one sign of such work going on. Below, a Year 9 student checks with the teacher (Tom) if a newly created way of thinking about measuring volumes makes sense. .

Tom:

.

So if I wanted to know what your, what your volume was, you'd get a big dustbin, and you'd get in it, and you'd get under the water for a second and you'd see how much water overflows.

Student 1: You might get killed trying to get out. Tom: Well you have to do it very carefully, under strict controls. Student 2: Sir, erm, say, you've got a massive swimming pooi, like say about thirty people, and you've got, say, twenty people going in it, you'd put one by one and then you'd measure Tom: measure how much it grows, that's right, that's it.

Sometimes students who want to test out an idea, or who find difficulties with their understandings, will speak up, but the extent to which this happens

that in right? [points], there it's though as sky the in looks it and star a see we if So us. to lines straight in space. through way the all — yes? — space through way the all comes it And Right? way. long a travelled they've — right? — see can we that light of sources furthest the are stars the that you with agree I'd —

.

.

Leon:

there. them see we because are they where are things that round, way other the reason we thinking, everyday in because only if easy, be cannot It travels. light way the of terms in explained be to something into are' really they 'where things see we that fact obvious and simple the making of problem the himself sets Leon follows, what In explaining. needs which but expected, be to obviously not something into obvious seems what making of case the is It expect. to what and think to how disturbing of differences; creating of case difficult very a of example an with conclude We

explain?' to 'Nothing out. checked was it that ensured Steve and discovered Steve which idea an had Steve's out, it checked and idea an had student Tom's Where previously. ideas Daniel's heard having be, to going was answer the what of knowledge full in question a asked Steve So thought. same the had probably who class the in students other the would Nor stuff?' watery this for name right the water 'Is asked, have never probably would Daniel sir. Yes, Daniel:

water? some got you have wak—, some got you have moment, the at tube your in got, you have Daniel, So, water? into melted It Steve: water. into melted wax the mmm, Arr, Daniel: experiment? the in happened what's Daniel, happened. what's say to names by people pick to going just I'm because up, hand your put to need don't you moment the at and out, shouting people want don't I names. people's say to going I'm happened. what's now people certain ask to going I'm and experiment this in happened what's about tables, the of most to spoken I've and out find to trying been I've mmm, Now, Steve: tables: of number a at groups in working students 7 Year of teacher the by 'tour' classroom a such of results the shows excerpt ing follow- The whole. a as class the to discovered problems the 'publishing' then and questions, asking and done being work at looking class the tour to is possibility One ideas. or difficulties out bringing for students on ility responsib- place to always teacher the for however, necessary, not is It low. be to tend will proportion the controlled, tightly is turn-taking where classrooms in Clearly, expression. overt find cases such of proportion small a only that believe we arise, occasion on can which questions such of number erable consid- the From teacher. to teacher and class to class from widely varies 36

CLASSROOM THE IN SCIENCE EXPLAINING

OPENING UP DIFFERENCES

37

there— where really is it? If it looks to be over there [points], is it really down there [pointsl?

line — over

Student: No. Leon:

Has the light gone, sort of like, from over there, 'nee-ee-um'

[gesture and sound of rapid motion in a curvej something like that? Student: No.

What's the light done? It's just gone 'zy-oom' [gesture and sound of rapid motion in a straight line] straight to us, yeah? It travels in straight lines, right? Do you see what I mean? If I wanted to smack you across the head, right? — I don't — I don't — I never would want to do that — but if I wanted to do that, right? Or give you this pen. If I wanted to give you this pen, yes? Would I — would I put it into your hand 'cos really your hand's there? Where really is your hand? Student: There Leon:

Yeah. And I know that, don't I? How do I know your hand is in that line from me to you? Student: 'cos you can see it. Leon: But how can I see it? What? — there's light in the room, there's light coming in, and where is it shining? Leon:

Student: Everywhere. Leon:

Is some of the light shining here? [points to student's handl

Student: Yes. Leon:

And then what does it do? Shines on to you?

Student: And reflects. Leon:

It reflects. To me? Does it reflect to me in curved lines or in

straight lines? Student: No, straight lines. Leon: So it's coming through [gesture towards teacherl —

so if I want to put this pen in your hand I can go straight along the line that the light's coming from, and put it in your hand — right and that's in your hand isn't it? —

We see Leon here tackling one of the most fundamental problems of explaining scientific explanations, that is, dealing with cases where there seems to be absolutely nothing to explain. Indeed what is about to be explained is that which, in everyday thinking, itself does the explaining. Leon has not only to make it seem a problem that he can see a hand where it is, but has to get

further involved in making it a problem that he can see the hand at all. Instead of a story of light travelling from hand to eye, common sense has a story of light 'everywhere' which is a condition of seeing but not a mechanism of seeing. People do the seeing — the presence of light helps. Notice the response, 'Everywhere' to the question, 'Where is it shining?' (from Year 8).

A limiting, but fundamentally important case of dealing with expectations is thus that case where there are no expectations at all — the case of the seemingly obvious. There are more than a few such in science. Things fall when we let them go and stop when supported by the ground. It is obvious

expect?' you do 'What ing head- the under grouped mainly are These that. to counter runs which ledge know- and know they think students what between is difference the when is other The next'. do to going are we 'What heading the under grouped are These know. to need they what and know not do students what between is difference the when is kind One kinds. main two into grouped be usefully perhaps can chapter this in discussed difference creating of ways many The

difference of kinds main Two them. with happens what influencing — yeah? chemicals, of sort some be must there mean, I Yeah, light? the towards grow to know, to were, it as know, they would how What, know? they do Leon: How leaves? their drop to autumn the in know plants do how .

.

.

explained: be to something into 'obvious' something make to trying case, different a in again, Leon is Here explained. be to not is it explains; It not. is what and animate is what us ing tell- 'animate', being of meaning the of part is itself' by 'Motion why. and it do they how — here explain to something is there that anyone persuade to hard is It themselves. by around move animals another: Take here? 'gravity' of need What explained. be to event an as not events, explain to it use we and CLASSROOM THE IN SCIENCE EXPLAINING

38

Chapter 3

THE CONSTRUCTION OF ENTITIES

New things from old A teacher, David,. is talking about teeth: David: Your teeth are part of your digestive system, your teeth take the food, smash it up into tiny bits, bite it off, smash it, make it into tiny bits.

What is going on here? Several accounts are possible: David is explaining the function of the teeth; he is explaining a part of the process of digestion; he is developing 'the concept of the digestive system'. But what strikes us most about it is that the teacher is trying to change what 'teeth' are for the students. The students already know a lot about teeth, from early childhood and beyond. They know about what they can do and what can be done to them, about where they are and what they are. They have been constantly reminded to clean them. They may remember losing milk teeth. They have experienced dental care. They know not necessarily consciously — that teeth are important in smiling. They have been prevented from biting other people. But now the teacher wants them to imagine teeth differently, not now as a part of the mouth, and not now in relation to feelings, but as a component of a biological system. Words like 'chew' associated with intentional action are avoided; instead the teeth are presented like machinery —

('smash it up into tiny bits'). So our account is that the teacher is busy constructing a new entity, the entity 'teeth in the digestive system'. Teeth are being given new meaning, just as (say) 'banks' are given new meaning when

what and them, to done be can what do, can they what establishing means them constructing And constructed. be to have — entities biological relevant the — needed resources the explanations, biological the to get to So lunch. having of business everyday the of actors human social the all at not are tion diges- of story the in actors biological The processes. biochemical and juices organs, of made world, different a in story a tells explanation biological The wants. satisfies It satisfying. personally as well as sociable necessary, as well as nice is food that is eating of explanation everyday The explanation. of nature the from derives which reason a world, their change to reason a is There bodies. own their including to, added and changed being are world their up make which — entities the — objects The world. the in objects as themselves regard to and persons as themselves outside stand to asked being are students The on. going is pointing and gesturing of lot A 'Here.'). 'No.' .' somewhere. here 'Down here.' 'Down is?' that think you do ('Where now and here things on focus intense the Notice telling. .

just not But things. them telling of matter a be to simply seem changes these surface, the On bladder. the and intestine, small the intestine, large the bodies, human of parts various of understanding their changing also is He system. digestive the of understanding students' the changing is David body. your of out waste takes that system, excretory your of part is That system. digestive your of part not It's bladder. a got You've David: bladder. The Katie: got? you what've Katie, got? you have else What anus. the at the, at up finishes actually and back, comes and around, then top, the across goes It good. right, That's David: top. On Student: go? intestine large the does where here, sits intestine small The intestine. large a got You've David: intestine. large The Student: got? we have else what else what anyway, but here, about they're maybe or okay, here, about are intestine small The big. really it's cause intestine, 'small' the called it's why knows goodness intestine', 'small the called it's fact, In here. about It's David: Here. Student: No. Student:

somewhere. here Down David: here. Down Student: is? that think you do Where intestine. small The David: intestine. small The Student: got.

you've bits the of some of names the me Tell system. digestive your in got you've know you do bits what start, we before So

David:

construction': 'under system digestive the of more is lesson 10 Year same the from Here money. gets one where Street High the in place a instead economy, invisible the of part as economist an by considered as of

40

CLASSROOM THE IN SCIENCE EXPLAINING

THE CONSTRUCTION OF ENTITIES

41

they are made of. We showed in Chapter 1 how this way of looking at what is involved in meaning derives from combining a Piagetian viewpoint with a semiotic one. In Chapter 1 we also briefly discussed the nature of explanations and the special nature of scientific explanations. We presented scientific explanations as analogous to stories of how things come about, but with the actors in the story often being unfamiliar and new. Here we see a small example of the introduction of new actors. These particular new actors — these new entities — are not especially new to students, however. That is one good reason for the teacher wanting to make teeth seem strange, so as to suggest that there is something new about them to consider. Later in this chapter we will see much less familiar — much stranger — entities under construction, including some that it would at first sight not seem reasonable to think of as 'entities' at all. Here is one further extract from the same lesson on digestion. The class are looking with the teacher at a dissected rat. Student: What's that black stuff? That bit there is the liver. David: Student: It looks like it's been smoking. That bit there is the stomach, David:

Katie, that bit there is the

stomach. Students: [Light laughterj Okay, and now what she's looking at, is this stuff here, which David: is the liver. People don't realise how big the liver is, livers are really big. That great chunk there is liver. So when she says it

looks like it's been smoking, she's thinking that this is in fact lungs. If you were to look at the lungs of somebody who's been smoking, they're not pink and soft like they should be, they're black and gritty, and that's why, that's why you said that... nicotine and tar. . . Anyway, that's the liver. Now, the liver, is a place where food is stored. The liver's part of the digestive system, I guess, because eventually food is taken from the — from the gut, via the blood, to the liver, and stored in the liver till need it's needed, okay?, so, for example, if you have for lunch four Mars bars and you.. . four Mars bars — then the stuff would go to the, to your gut, all the sugar in those Mars bars, which would be a lot, would come straight back to your gut, and into your blood, and your blood would be like treacle, because it'd be full of sugar, so in fact, it's taken straight to the liver, and it's stored in the liver, and small amounts are let out, uh, through the course of time, okay?, so that's the, that's a kind of storehouse where things are stored, so the liver stores food, it does a whole load of other jobs, but it stores food. This seems like the naming of parts. But it quickly develops into an explanation of what the liver does, a story about digestive events. Starting from a student asking, 'What's that?', we get a story about sugar and livers, not just

Other field. another in term the of understanding his employing standing, under- tentative own his create can he if seeing already is student One work. that in participants active be to have will students the and time, of period long a over work, of lot a perform to have will teacher the develop, to term the For more. something become will it that promises effectively teacher the but them, to word a lust is 'density' yet, As new. something encountering are students these examples, previous in As is. it way a In got?

you've information much How

Tom:

Yeah. Student:

disk? computer a like mean you what, way, a in well, No, Tom: disk? a on as same the it Is Student: it. measure can you how at look a have and go to going we're then and means, density what you tell to going I'm Now, Tom: know. I Student: density. means, word this what mmm, have is now do to want we what listen, Right, Tom:

about, chat

a

density'. of concept 'the to class 9 Year difficult sometimes and ability low relatively his introducing of task unenviable perhaps the has Tom, below, extract the in teacher The

entity conceptual new a Making teacher. the by offered explanation for resources of and explanations of sense own their make to also is work Their too. that be may it though — hand to world the in or themselves in already knowledge discovering always not is work that but do, to work have students The them. to done have and do can things what from meanings new constructing of part is which explanations, other in play may entity new a role what illustrating of but that), do also may they (though phenomenon a explaining of primarily not function, the have tions explana- Some explanations. making for resources become will which entities — entities modified or new constructing together teachers and students volves in- explanation with do to work the of much that case a made have We rats. in livers about not general, in livers about talking are we that implicitly says livers human as lob same the do livers rats' that assumption — unmentioned indeed — easy the And know. already they what replace, to not to, add to meant is entity the about knowledge new the that students the tells context, familiar a of choice its with given, is explanation the way The possess. already students the which foods and livers of knowledge to and it, at looking by gained have children the knowledge perceptual the to things: other several to linked smoothly is entity new This liver. the — entity biological the constructing of job the of part indeed is explanation, an in role a liver the giving explanation, the So it. to done be can what and do can it what is, liver the what this: for reason good is there And naming. a CLASSROOM THE IN SCIENCE EXPLAINING

42

THE CONSTRUCTION OF ENTITIES

43

students are likely to be doing the same even though they merely seem to listen. The way this student thinks ('the same as on a disk') points to another vital aspect of the construction of entities: building them by analogy with others. Interestingly, the term 'density' as used in the label, 'Double-sided high density', on a computer disk derives from an analogy of information density with material density — from an analogy with the very scientific term 'density' which the teacher is here involved in constructing. The student, more familiar with computer disks than with ratios of mass to volume, does the same job backwards. We return to the role of analogy and metaphor in Chapter 4. Even at this early stage, it is not hard to see that something new is coming into existence, a new thing which may still seem to be a 'term', a 'word'. And the teacher talks in a way which has an air of 'explaining terms': talking about 'meaning', defining terms and giving examples, as below:

Tom: Density is how much stuff there is inside a thing. Now, to give you an example of what I mean by that, Michael, that's made of wood, okay, this piece is made of metal, which one do you think is heavier?

Rather quickly, however, the teacher moves from words into activities which seem quite different. In fact, he stops talking about density and puts pieces of wood and metal before the class, discussing which is heavier and which is bigger, and he does things together with the students, having them weigh various objects, and having them look at the objects to make guesses of their size. The work is directed at things, not at a word any more. The teacher dared to assume, with a 'lower ability' class, that the students would understand that he was talking about 'density', when he was actually talking about 'weight' and 'wood' and 'metal'. And the assumption held. The students can 'read' this kind of classroom work. The teacher does not refer to density again until some time later. When

he does, he uses a new term, 'mass', and he places a qualification on the things in question. They are now not just things, but things which are the same size.

Tom: That one would sink. This one is denser than this one, so two things the same size, one has got more mass in it than the other one.

What is striking here is that what the teacher is saying cannot yet make sense to the student. The experience is very familiar. New definitions generally seem distinctly opaque (if the reader is not persuaded we advise look-

ing at some definitions of 'money' in an economics textbook!). Of itself that is not necessarily a problem; at various points in their school life students will encounter similar and no less mystifying 'definitions', which will later — and only gradually — come to make sense. In this lesson the teacher moves quickly to give the definition a more permanent form, and makes the students write it down:

idea same the is it that each; in way same the in used be to is idea new the that cases; parallel all are these that things: several 'says' repetition The Tom: Right. Wood. Student: balsa? some or wood of piece A cubed? centimetre every for grams more got What's question. a asking I'm down, sit no, No, then? cubed centimetre per grams more got has think you do what Tom: right, one, another try to want you be, must it so done, Well

glass. of Piece Student:

polystyrene? of piece a or glass of piece a cubed, centimetre every for grams more got has think you do what Tim, okay, lead of Piece

Tom:

lead. of Piece Student:

wood? of piece a or lead of piece the cubed, centimetre every for grams more got has is, think you do what Meesha, do. to what know you if see and look a have Let's

Tom:

examples: successive several in words of form a and meaning a repeating through rehearsed is 'density' of form last The done. now is job the that assume not does teacher the And structed. con- are existence', into 'come gradually talk teacher's the of entities The

cubed cm every in there are stuff of grams many how object an in is there stuff much how of measure a one other the than it in mass more got has one size, same the things two thing a inside is there stuff much how

• • • •

transformations: successive the are Here constructed. gradually is 'density' lesson, whole a of span the Over got. you've that space of cubed cm every in there are stuff of grams many how is in interested be you'd what something, of density the know to wanted you if So, okay. cubed, cm in volume grams, in measured is mass measure, you what know you So Yeah. Tom: again: transformed is density of definition the objects, of variety a of masses and volumes the measuring activities practical after lesson, the in later Much density. of not mass, of definition Newton's was this that matter No

object.

an in is there stuff much how of measure a is Density I. matter doesn't it being, time the for stuff it call just We'll Tom: Density 2: Student Tom: [1 Density is Density 1: Student whiteboard] the on writes teacher [The

what down write

is do

down. this copy So is. density to going we're thing first the So, .

.

.

Tom: 44

CLASSROOM THE IN SCIENCE EXPLAINING

THE CONSTRUCTION OF ENTITIES

45

in each. It repeats one of the things one can do with the entity 'density', namely deciding which of two things is more massive. And the form of words ties an expression to what the class have just been doing with their hands when measuring the masses and volumes of different objects. By having the students write down the definition the teacher indicates that density will be recurrently important in their work in science. But terms such as 'density', or 'stuff', do not make sense simply because of the def-

initions. The teacher may say what density is, but the students do not, as a result of that saying, know what density is. To say what density is, isn't to mean, but is effectively to make a promise that the utterance will be meaningful in retrospect. Students can recognize that these utterances have a

particular status; from the slow pace of speech, a particular intonation, their repetition, and the fact that they are often to be written down and remembered.

'Density' will continue to be transformed. Over several years it will be implicated in a wide variety of relations with other entities — floating ships,

'floating' continents, gases, mercury and barometers, the atmosphere and the weather, convection, and even in ways of distinguishing chemical elements. It will participate as an entity in a multitude of explanations. In all this, as it becomes related to other things, it will be undergoing yet further change. The students will be learning more of what you can do with this entity. For example, in Tom's lesson, density cannot be a property of a gas, since, for the students, gases do not yet clearly have any mass. When eventually the density of a gas is considered, both 'gas' and 'density' will be changing into something else, each a little different. Density will now apply to seemingly intangible things. And a gas will as a result come to seem more tangible, more substantial. Thus, in these later incarnations, the entity 'density' may not obviously be changing, but change there will be. 'Density', like

other entities, does not come into existence and remain what it is for all time. Meanings of entities undergo constant change, though where the change is less dramatic it may be barely noticeable.

Why 'entities'? We referred above to the teeth and the liver as 'entities'. In the discussion of density in the section which followed, we have referred to 'density' variously as a term, a word, a concept, an idea; but we have also, and with less obvious justification, called it an 'entity', as if it were to be thought about in the same way as the teeth or the liver. Why insist on it as an 'entity', implying that it is constnicted in the same way as others? There are several reasons.

First, we do not find it helpful to distinguish 'explanations of material things' from 'explanations of concepts'. Certainly verbal forms of definition

play a role in the latter which is not so obvious in the former. But the discussion of material things in the classroom involves a lot of definition. For example (coming from Year 10):

— function a suggest or identity them give would which features individual the without blocks regular bland as way, special a in presented are They way. new a in seen be to are materials The objects. make to them use not does he but objects, make to used commonly are which materials provides Tom density. 'concept' the about talk the and feel) and look their to ing attend- and materials different many of blocks (handling provides Tom ities activ- material the between made be can connections perspective, this In iob. of kind same the ways many in is meaning their learning But 'livers'. with done be can what as thing of kind same the not is 'density' with done be can what course Of 'livers'. as well as 'density' 'electricity', as well as 'acceleration' 'planets', as well as 'verbs' and 'nouns' covers formulation a Such make. or from made be can it what and it to done have can do, can something what are they possibilities; of constellations are meanings them, understand we As made. and created are reason fundamental, again and fourth, A to meanings how with do has blood. the in levels sugar controlling insulin about one as form same the fits gravity by produced as motion (say) of explanation An about. learn to has student the which things the as entities) (the actors the of think can we and roles, their out play actors which in stories like being as explanations of think can We explanations. of account uniform a give can we kind, some of 'entities' as explanations scientific into enter that elements the all of thinking By fundamental. is reason third The another. one affect which things as about talked also are but concepts, are accelerations and Forces time. same the at real and conceptual similarly are wave a or bond chemical A actions. proper own its with entity tangible a into needle') compass a of directions of locus ('the concept this turning teacher a of example an give we 6 Chapter In cept. con- a and thing real a both is field magnetic A itself. science in clear-cut all at not is conceptual the and material the between distinction the Second,

on? stuck what's quickly], very [said ribs and column spinal skull the onto stuck what's Now, it. onto stuck like yeah, end, the on Appendix, Leon: appendix. like Urn, Student: Appendicular. LAR. [1 icu [] END [1 P double A appendicular. be, will skeleton, the of it, of part next The right. part, main the stem, main The something? of axis the like, what's, all, after Because Yeah? ribs] his touches [teacher ribs and Leon: column. spinal Skull, Student: end, the at column said I skull, column, spinal skull, Umm, Leon: it? in What's Student: skeleton. axial the in what's say to want you brackets in and L, A I X A L, A I AX axial, down, it write are, They skeleton. human the to are there that parts, two those learn anybody Did parts. two are there though as it classify we but part, one there's and part one there's and shlip, go, can you like Not really. not Well, sections. two skeleton, human a to parts two are There Leon: .

.

CLASSROOM THE IN SCIENCE EXPLAINING

46

THE CONSTRUCTION OF ENTITIES

47

that is, they are presented as 'substance' rather than 'object'. Where a steel spoon would have said, 'use me', the teacher's regular steel blocks in the context of the lesson say 'measure me'. The material objects are being transformed too, into things which are measurable in three dimensions, that have volume and mass, for which the relation between 'the space they fill up' and their massiveness is salient and important. Thus materials get new possibilities and new meanings. And all this looks forward in the curriculum to a time when materials like these are to be seen, not as stuff with which to make things, but as stuff made of something — of atoms and molecules. These kinds of transformations are common and fundamental to science. Eating becomes digestion; falling becomes the effect of gravity; our stable home, the Earth, becomes a rocky ball hurtling through space; what parents pass to children becomes DNA; feeling unwell becomes an affair of microbes;

plugging in the electric kettle becomes a current flowing under a potential difference; and so on. It is not enough to say that these transformations just involve knowing a bit more. They change the inhabitants of the world. We take up this theme of transformation again in Chapter 4. To think about how entities are constructed is to think about how they are transformed. Everything new is made from something old. Some entities made in the learning of science are radically new, but there is much seemingly mundane construction work to do as well, as here in Year 9: Right, as Katie correctly says — sorry, Donna — Donna correctly says [teacher holds up an object to the classl that is a, all together

Tom:

Student:

Tom:

now [?1 a plastic tube. Measuring cylinder, it's not a plastic tube. Right, it's a measuring cylinder, okay.

However, to see a plastic tube as a measuring cylinder is to do more than learn the name of a tool. To understand the entity 'measuring cylinder' is also to understand more about a different kind of entity, 'volume'. And there are not two distinct activities, 'learning the concept volume' and 'recognizing measuring cylinders', there is just one, with 'measuring cylinder' and 'volume' coming into existence together. The measuring cylinder is significant because of its relationship to the concept 'volume', and the concept 'volume'

may in large part develop through the use of measuring cylinders. Their features — their markings for measurement, and their three-dimensionality, help 'carry' and concretize the notion 'volume'. We can see something of this complex joint construction process going on in the following, with the same class:

Tom: Right, now let's decide. Volume is now — [1 Yes right — [the teacher raises the measuring cylinder in front of the classl it's the amount of space something takes up, the volume is like the amount of space something takes up [teacher starts pointing to the measuring cylinderl

so if I build it up to 100, Kathleen, that means that that is holding a 100 centimetre cubed worth of space, or worth of water, yes?

are'. they 'how about is do' they 'what Here, screen. television a on light making or current electric an carrying electrons were it if be might it as nomenon phe- a explaining in yet as part a plays which something not is do' they 'what But do. they what and things on here focus the particularly note We electrons. are there course of And carbon. and boron elements are There electrons). of arrangement of forms are (which is or 2p, as game) this to outsider the to (mysteriously to referred entities the are There contain. atoms their particles of numbers the and properties chemical by simultaneously patterned elements chemical —

—

of display a — table periodic the entity, the is There construction. under here are potential, future important and large with resources, explanatory Several 240—1) 1990: (Lemke

before. from notes the from also is This orbitals. — confining — those within anywhere be can they And electrons. Six tablel. periodic to Ipoints Here Carbon. Carbon. Teacher: Carbon! Carbon! Students: ?I [ What's you? it? said Who Teacher: Carbon. Student: here one I here one here, one here, one here, one here, one have to have you'd So electrons. seven [1 uh have That'd be would That Teacher: —

—

Boron?

Ron:

Ron? I configuration? this by represented being is element what is, the in electrons two 2s, the in electrons two the in electron one have I If Teacher: the in electron one atom. an in electrons of configuration electronic particular a by represented being is element what asks teacher The Science. Talking book, Lemke's Jay from example an borrow we this illustrate To explanation. involving as seen be to are activities classroom of range wide very a way, this in sidered Con- depend. will schooling later which on resources creating by often ena, phenom- of variety whole a explain to used be may which resource a create to is but question, in immediately be may which phenomenon particular explain to simply not thus is explaining, and teaching, of point The together. bond atoms F

a

how at or flow, or move things how example for at explanation, of classes potential future at directed is classroom science the of work the penetrates, rainwater which to soil of depth the say, phenomenon, particular a for tion explana- an find to concerned be well may scientist working the Whereas built. be may phenomena of explanations which with entities the structing con- to but phenomena, explaining to just not however, devoted, is classroom science the of work explanatory the of Much about. comes something how tells It explanation. an clearly is bar chocolate a digesting about story David's

explanations for Resources 48

CLASSROOM THE IN SCIENCE EXPLAINING

THE CONSTRUCTION OF ENTITIES

49

This particularly complex set of interrelated entities is valuable for its future potential. They will make it possible to explain such things as the differences and similarities between chemical elements, why some are metals and others are not, why some react easily and others do not, why water has two hydrogen atoms for every oxygen one. Whilst a description of all of these

entities could perhaps be got into a chapter in a book, a compilation of explanations of all the phenomena which they can be used to generate could fill a library and still not be exhausted. The example is extreme. A simpler case is the following, in which Steve is teaching a Year 7 group about melting: Steve:

Shamir?

Shamir: It's liquid. Steve: Right. Okay, it's a liquid, like water, it's a liquid like water. Can

you just explain what you mean by that. Shamir: It's hke, umm, it's runny. Steve: It's runny. You can pour it [teacher picks up test-tube] you could pour it out of the tube. It's a liquid.

'Liquid' is much more than the 'correct scientific term' for runny things, though that may be how it seems at that moment. 'Liquid', along with 'solid' and 'gas' will gradually be transformed into 'states of matter'. And the reason to do that is not at all a matter of terminology. It is that different kinds of explanation are appropriate for accounting for these different states, and also that these different states play very different roles in creating explanations of other phenomena, whether the strength of bridge girders, the way to get a balloon to rise, or under what pressure oil has to be pumped down a pipeline. Thus the 'terms' solid, liquid and gas are pointers to different kinds of explanation. They help organize knowledge about differences and overlaps between explanations. Our conception of 'entities' as resources for making explanations embraces a very wide variety of things, an 'ontological zoo'. A few examples might be: water, energy, animals, fluids, density, amplitude, convection, evaporation, newton-metres, mass, volume, electrons, electron shells, line graphs, equations, variables, friction, cubic centimetres. Even this small sample points

to the enormous amount of work which is required to build 'worlds' in which these things make sense and can be used. The list does not distinguish material and abstract things. Distinct though they are at one level, for us they are all 'entities' at a more abstract level, because of the uniform way they enter into explanations. Providing resources to be used later obviously has its problems. It may seem to students too much like a case of 'medicine today, jam tomorrow'. For this reason, teachers need to provide effective motives for attempts to construct entities. These can be of many kinds, from appealing to the exigencies of the syllabus to involving the students in thinking out how things might be. A good example of the latter appears in Chapter 7, where a teacher gets a class to think through with him what joints in the skeleton might be

girls'. as same the just frightened get 'boys air: the in is gender of meaning the in shift possible A hormones. sex-related on ier earl- touched has which lesson, whole the of context the in so does boys?', and girls for this 'Is asks, who girl The minds. students' in them of many time, same the at on going are constructions many but one not always, As yeah? active, pretty something for ready get to going you're get, to trying you're though, as sounds it Leon: [?]Nasma, do to ready get to trying you're though as sounds It Leon: Student:

do? to ready get to trying you're like sound, that does What right? Food, Food.

Student:

laughter] [Student Spree.

?I

[

Leon: [?} and Oxygen, Oxygen. Students: Leon: contains which blood, of Lots

Blood.

Student:

body? your round get to trying you are What fe-toom. fe-toom, bodyl his across gestures large very [makes goes toom, toom, toom, chest] his over gestures small Leon: [makes going just of instead heart your and yeah, Oxygen, Oxygen. Students: Leon: particularly Well ?] [

Air. Students:

of? lot a get to trying you are What again? back come then and there about to down go to diaphragm your and here, about to up come of sort to cage rib your want you Leon: would why lungs, your want, you would []Why for? it What's Ohhh. Student: girls. as same the just frightened get Leon: boys the Yeah, yeah. one, this does everybody well well, Yeah, boys? and girls for this Is Student: yeah. Leon: adrenalin, produces it and gland Ad-re-nal Myra. done, well Yes, adrenalin? makes what That's Student:

whiteboardl the on

gland' 'adrenal [writes gland Adrenal L. A EN R D A gland, adrenal the called gland another that's umm, so, umm, okay, Umm,

Leon:

student: 9 Year a by it about asked been having fright, a get you when happens what about class the questioning by case this in hormones, of working the of examples particular of number a for time makes but mones', 'hor- entity the up building is teacher the below, example the In sugary.

something digesting of process the on that just doing was David familiar. preferably real, something of explanation partial some in use to put be can 'entity-coming-to-exist' The motives. providing of ways other are There together. class and teacher by constructed co- are entities that so students with work to able are teachers Some like.

50

CLASSROOM THE IN SCIENCE EXPLAINING

THE CONSTRUCTION OF ENTITIES

51

In all these examples, the teacher's talk is crucial, as an example of how to talk, indeed of how to think. The very point of constructing entities as resources is that they need to become, not things to think about, but things to think with. This is the importance of teachers demonstrating in their own talk a process of thinking which will allow the formulating of questions and of answers to questions, that is, demonstrating how to think with and manipulate one's knowledge.

And not only that. It is also part of constructing entities as thinking resources for students to try using them as such. Having worked with a Year 8 class on light rays (another entity at once abstract and material) Leon's next

teaching step is to challenge the students to put them to use: Leon:

I want you to draw something that looks like this.

Student: A wiggly line. Leon:

No, like this. Glass rod. Okay, that's just a glass rod, a bit of a glass rod. Draw this please all of you.

Student: Pardon. Leon:

Draw this. It's a bit of the glass rod, and the question is, how can light, which travels in straight lines, OK, light travels like that, straight lines, how can it, erm, get to the end? [I How can it possibly do it?

The answer to such a question is an explanation, a possible story about the behaviour of certain entities (here light and glass), and the way in which this

story accounts for how an event might come about. We don't reproduce a student's answer above, because there wasn't one. Leon knew that this process — making up an explanation — would take time; and he made time and space for it. For a substantial fraction of the lesson, students worked on the problem and Leon moved amongst them addressing problems they raised about it.

Process entities Scientific texts are well known for their high concentration of events and processes presented as if they were things. Simple examples include evaporation, crystallization, ionization, speciation, oscillation. Any scientific textbook

or journal will yield a multitude of them, as transparent as 'magnification' or as opaque as 'commensurability oscillations in the resistivity' (culled from a relatively non-specialized journal). Their presence is not due to the barbarous linguistic habits of scientists. They exist in texts and talk as entities because they exist in the thinking of scientists as entities. They are, as we said before, things with which to think. Our next example shows a teacher (Steve) working on constructing a process with Year 7: Steve:

I want to finish off the lesson by just making sure you understand the word 'melted'. If you get a teaspoon of sugar and put

are there retina your In work. hard the all does that brain your it's and brain, your to messages sending by respond they — send they them on shines light when is do they what fact in and II things do they OK, respond, they them on light shine you if so light, to respond retina the in Cells OK? retina the Alaw in cells of types main two are there retina the at look you if retina: the eye, the of part of account 8) (Year following the is example further A skeleton). the of parts and system digestive the of (parts above examples two seen have We ponents. subcom- physical straightforward are entities of parts the cases, some In 'lungs'. entity the in up packaged meaning the to contribute facets these All system. atory respir- the entity, conceptual a of part and body, the thing, physical a both of part themselves are and vessels, blood and passages air as such parts have lungs The cup. a of meaning the to contribute features These handle. a and base a rim, a space, hollow a has cup a packages: complex as come Entities parts. are they which of entities other the and have, they parts the of': made are they 'what is It examined. be to remains entities for meaning making of aspect further A them. to done be can what and do can they what of terms in entities for meaning of construction the at looked mainly have we far So . .

parts their and Entities etc. 'excretion', 'radiation', 'convection', 'meiosis', 'hydrolysis', 'digestion', as such entities objects, material hardly way other this in are, which science for study' of 'objects more yet find we here and things', 'material just hardly are science interest which entities the that point the made earlier have We example. for discussed, melt' 'the see we glaciers studying in and iron smelting In things. like something into them turn does them examining in and processes, such examines carefully it that science of characteristic important an is it entity, an be to 'melting' as such process a consider initially not would one although that above argued We other. each as same the not They're melt. and dissolve between difference the understand you sure make So dissolves. It Steve: dissolves. It Esther: tea? in sugar to happens what describe to use you do word what Esther, that. describe to word another there's melting, not is that's liquid, a with it mix you when disappears which solid a got you've if what, important, very is this and it, mix you when appears dis- which solid a have you If melts. it liquid, a to solid a from changes something If melt. will it hour, an half for hand your in it hold you and ice-lolly an get you If melted. not has it but anymore bottom the at bits little have don't you, can't, you and liquid, the into goes It I melt. not does it it, tea, of cup a in it CLASSROOM THE IN SCIENCE EXPLAINING

52

THE CONSTRUCTION OF ENTITIES

53

actually two different types of cells — two main different types

of cells. One of the cells responds to coloured light, OK? The other cells respond more to black and white light. OK? When it's dark in the evening at night times and so on, can you see colours? Or do you tend to see in shades of black, white and grey?

Student: Black, white and grey. Student: You can see green. Alan: You see green? Student: If they're bright. Alan: You certainly don't see the variety of colours that you see during the day — OK? — most of you have probably noticed that you see things in black, white, shades of grey in between. that .

is because one of the types of cells in your retina. . . responds more to black, white and grey than to colour. And it needs less light to do so. In introducing parts, Alan focuses —

as

in many previous examples — on

what they can do and what can be done to them. The role which the parts can play in an explanation, here of night vision, is an essential part of their meaning. One expects an organ like the eye to have parts, but some entities have parts much less obviously. Here is Leon stressing to Year 8 that lack of obviousness in the case of light itself being made of colours: Leon:

Have you, did you ever have one of those Barbie dolls? Yeah? Okay. Right, excuse me, if you, if you, take this leg off, and this leg off, and this arm off, excuse me, this arm off and the head off, right? You've got all the parts, yes?

Student:

Yes.

Leon:

Stop. . . the Barbie doll, you took the bits off, yes, and it's just like parts now. What happens if you, put this leg on and this

leg on and this arm on and this arm and it's head on? It's a Barbie doll. So if you've got white light, yes, and you can separate it into all its colours — red, orange, yellow, green and blue and violet — what happens if you put red, orange, yellow, green and blue and violet back together again? Students: They're white. Leon: OK, right, that's how it works. I didn't think you'd get that one 'cause it's a hard one, okay. Leon:

Leon enforces the not so obvious idea that white light can be 'taken apart' into colours and then 'put together again' by the analogy with a doll which can obviously be taken apart and put together again. The analogy is not one which says anything about what light is. It is one which says something about what can be done to it. Just as entities, in our way of thinking, are not at all restricted to physical entities but can be conceptual, so parts can also be conceptual. Chapter 7

the explain to used is scheme This influences. various of actions the between balances and checks controlled of terms in for accounted is organisms logical bio- in stability example, For form. in similar are but detail in differ which explanation, of kinds about learning much as just is science learning But enon. phenom- given a for account to entities particular use explanations Particular

explanations Prototypical them. to done is what or do they what by explained is parts the of nature the again Once box'. dioxide 'carbon the to or from added arrows be to there expect to students the of reasonable very be would It atmosphere. the of out or into dioxide carbon of flows to rise give which processes of classes in part taking entities of classes of consist parts the that principle; structuring the on also emphasis — — is there But whole. structured a is cycle carbon the entity this that idea the enforce to serve may diagram, the drawing of act physical the on and here') over box ('a in filled be to parts of existence the on emphasis The limits. of sort those within it keep so middle, the in box a and here, over box a and here, over box a get to got you've that remember but box, a big how know you if first it write would I again, Respiration. respiration'. during ide . .

diox- carbon out breathe 'animals says box that — that's so OK, Elaine: out. it breathe We Student: air? the into get dioxide carbon the does how now Right, Elaine: it? isn't rainforest, the down burning not for reasons Two right. That's Elaine: down. cut not they're if and down cut Trees Student: air. the of out dioxide carbon take things other and air the into dioxide carbon put things some because time the all amount same the less or more stays that and atmosphere the in dioxide carbon - Right it. around box a draw and first writing the do to better be might it box a Draw atmosphere. diagram to [Points Elaine: the in dioxide carbon top the at started I —

—

.

.

—

.

—

.

.

1

diagram: a up builds she as cycle bon car- the of parts the explaining 9) (Year teacher the see can we Below cycle. carbon the or table periodic the as such structures knowledge diagrammatic and tabular crucial are parts with entity of kinds important other Amongst real. seem

entity abstract an of parts abstract these making into goes that work the there emphasize and force, of lines of' 'made as constructed being fields netic mag- of example the give we 6 Chapter in Similarly, transformed. is 'sound' entity the process that in and itself, — sound — thing the over laid and posed im- being is conception A 'frequency'. and 'wavelength' 'amplitude', parts conceptual the introducing as read be can which sound, on lesson a contains CLASSROOM THE IN SCIENCE EXPLAINING

54

THE CONSTRUCTION OF ENTITIES

55

control of body temperature, of hormone levels, and even of the rate of breathing. It may be termed a 'prototypical explanation'. In this way an entity which fills a certain role (e.g. control) in one such explanation, for example a hormone, becomes more than a hormone. It is also a regulator — a general class of entities (see Chapter 4 for an example of an analogy with an orches-

tra and its conductor, clearly intended to lift the argument to this more general level). And, of course, a hormone is already a class of entities, including progesterone and testosterone as members. An example of a lesson about a prototypical explanation and the classes

of entities it involves is one on weathering. The interchanges between the and the Year 7 students continually shift level, from particular cases to what they are cases of, and back again. teacher — Elaine Elaine:

—

So, what is weathering? What do we mean by weathering?

Yvonne? Yvonne: Weather can wear it away. Elaine: Right — not necessarily wear it away but [ Student: Damage it. Elaine:

?]

Damage it and loosen it, so that perhaps the surface looks crumbly. Right, so that's damage, to the surface of rocks or buildings, stone, brought about by things like wind and rain and frost — the different weather conditions — which is why it's

called weathering. Pollutants. Scientists think that pollutants might speed up this change, might make it go faster. What do we mean by a pollutant? Student: Something in the atmosphere. Something that pollutes the atmosphere. What do we mean by 'pollutes the atmosphere'? Student: Changes that makes it bad, like put bad fumes into the air or something.

Elaine:

Elaine:

Changes the air in a way that causes some kind of problem or damage. And how does that pollution get there?

The prototypical term 'weathering' is exemplified ('things like wind and rain and frost'). The general term 'damage' is illustrated ('perhaps the surface looks crumbly'), after being substituted for the slightly less general idea, 'wears things away'. In this lesson, this talk is leading up to an experimental activity in which students will see whether different concentrations of dilute acid affect different materials at different rates. Its point is that Elaine wants

the students to see the activity, not as testing the effect of acid on some materials, but as a prototypical explanation of pollutant concentrations altering rates of weathering.

Much of schooling in science necessarily concerns such prototypical explanations and classes of entities. Teaching about electric circuits is not teaching about 'this circuit here now', but is about how a current is produced by a voltage across a resistance. Teaching about gravity is about a

bubbly. and hot being it and out coming steam Er Sally: change? chemical the for evidence your was What Leon: chemical.

—

—

Er Sally:

one? Which Leon: yes.

—

Er Sally:

change? physical a or chemical a was it that conclude you Do OK. Leon: it. that's and — green went it then out, coming steam had and hot quite was it and bubbling was it down, and up going was it as And 33. to down back went then 60, to up went and 20 at started also [] urn powder magnesium the then And colour. reddish of sort a went they then and with start to grey were they — filings iron the in change colour a noticed also we and [I Er top. the at filings iron other few a then and — clear then and — bottom the at right filings iron was there so middle the in clear was it one, that finished we'd when [] er then and 30, to up went it then and 20 read thermometer the start, the at [1 and up go did heat the — urn And Sally: go. you off now Good, Leon: Yes. Sally:

there? thermometer the put you why that's So Leon: Yes. Sally:

here? pen hap- to going was reaction chemical a of, possibility a was there that be, might there think to reason some had you And Chemical. Chemical. energy? of lot a out gives often out, gives change, of sort what reaction, of sort What answer] them? between happen might think you did what — sulphate copper the and magnesium the and iron, the and sulphate per you were copto Because, expecting what happen the between it. that's Yes, up? go might temperature the thought you So rise. to thermometer the in stuff red the made — um — heat The suspecting? of sort you were What all? at in thermometer the putting for reason the was What on? carry you before Sally, something, say just I Can it. in thermometer a put also and powder magnesium put we one other the in and — well as it in thermometer a and — filings iron put we them of one in then and them of both in sulphate copper of bit little a put we Well

Leon: Sally:

Leon: Sally: Leon: Sally:

Leon:

Sally:

change. of prototypes between difference this identify can students 9 Year whether seeing is (Leon) teacher the follows, what In change. ical phys- and chemical between distinction the is explanations of kinds between distinctions schematic general very such of example An current). charge, (mass, object test a on magnetic) electric, (gravitational, field a by exerted force a to general, in fields to expanded is this on later mass; a on exerted force 56

CLASSROOM THE IN SCIENCE EXPLAINING

THE CONSTRUCTION OF ENTITIES

57

Leon: Anything else? Sally: Colour.

We at once notice the distance between the worlds invoked here. Sally talks mainly in the here and now ('hot and bubbly', 'went up to 60') and of what she saw. Leon is talking much more generally about types of change. The bridge between them is the attention, evidently expected and clearly given, to a temperature change and to a colour change — both symptomatic of but not defining of a chemical change. Sally moves between this somewhat general level and the particular ('a colour change in the iron filings — they were grey to start with and then they went a sort of reddish colour'); this being a change she sees as one 'in the iron filings' which Leon would see as a chemical change — reddish copper coming out of the compound copper sulphate. Sally noticed that the blue solution went clear but did not associate that with the removal of copper.

Here we have the beginning along a long road towards understanding different forms of explanation. The immediate props for understanding are simplified (transformed) versions of the chemist's distinction — temperature and colour change. The gap is at its most evident when Leon asks, 'what did you think might happen between them?', but isn't answered. His repair job to the question provides a heavier clue, to which Sally can respond. What we think we see here is practice in thinking in parallel in two ways, one particular and one prototypical. It is from the rough edges between them — the 'semiotic friction' we mentioned in Chapter 2 — that Sally and her listening classmates can learn. To conclude, we return to the subject matter with which we began — digestion to illustrate that general prototypical kinds of change need not just to be abstracted but also to be instanced. Here is the teacher, David, making sure that 'digestion' does not remain only a prototype; that what 'digestion' is in particular is also made vivid, immediate and concrete. —

David: So right — here [points at dissected rat] here is the stomach — yeah? — and the food, when it's liquid, gets squirted into the first little

bit of the tube there, which is called the duodenum. . the duodenum is where extra digestive enzymes get squirted onto the food to help — to make — digestion continue. .

language. reshaping as science knowledge, remaking as talking interdependent: deeply as them see we because indistinguishable often are science, and language knowledge, and talk chapter, this in story this of telling our In students. by, and for, produced explanations in and explanation scientific in metaphor and logy ana- of role the discuss we Finally, knowledge. scientific and science about messages particular carry which stories work, scientific about stories sulated encap- of on passing and creation the in knowledge, of reworking of kind special a consider then We science. school into transformed is knowledge that how show we community, scientific the in knowledge scientific from Starting telling. the in transformed always is knowledge that argue We class. this in students the for appropriate knowledge' 'school into transformed now is which community, scientific the by produced been has which knowledge the be may it or classroom; science the in built gradually been has that knowledge of kind the be may it life; everyday of experiences the from students by held already knowledge sense' 'common- be may This transformed. is knowledge which in ways of number a show to wish we now somewhat; changes focus our Now happen. can tion explana- of work the which in arena, shared a building in do to has teacher science the which work the show to tried have we 3 and 2 Chapters In

knowledge Transforming

KNOWLEDGE REWORKING 4

Chapter

REWORKING KNOWLEDGE

59

Change and constancy A central fact about languages is that, despite their appearance of stability and constancy, they are constantly changing. The source of change is clear: every act of communicating, every production of a meaningful sign, every understanding reached, is newly made. Every new-made meaning differs, however slightly, from the old one. Languages both change and stay the same because communicating necessarily implies both newness and sameness. Signs get meaning from their contrasts with others, yet make those contrasts anew each time. The source of constancy is thus also clear: new meanings are only possible by contrast with old ones. Scientific knowledge is also continuously changing. The 'amount' of scientific knowledge has been estimated to double every fifteen years. But it is also the case that at a given moment, scientific knowledge appears to be very stable, providing a settled framework for understanding the world. And this framework is what schools see themselves as teaching. The dynamics of constancy and change in knowledge are rather like those of language. Constancy there has to be because every piece of knowledge depends on other knowledge. Change there inevitably is, because of the drive to new understandings. A language community has to have ways of keeping its language both fixed and fluid. Similarly, a scientific community has to have ways of keeping its knowledge stable and constant, not to freeze it forever but — almost paradoxically — so that change is inevitable. One of the mechanisms of stability is schooling. It is no accident that in schooling knowledge is heavily policed; that 'right' and 'wrong' ways of thinking are sharply demarcated and differently rewarded. But this is not the whole story. Every telling, and every hearing, makes a little difference. Learning is an active construction; just because

the knowledge of one person can appear in another does not mean that it was piped across — with the implication that it travels unchanged. To teach is to act on other minds, which themselves act in response.

Knowledge in the teaching thus differs from knowledge in the making. Scientific knowledge, as stabilized in the scientific community, has to be radically transformed before its form is fitted to a given act of teaching. And in the learning it is transformed again, as students make their own sense of it. All these transformations happen not by chance, but through work. Thus an account of knowledge transformation is best thought of as an account of the reworking of knowledge.

Knowledge made and transformed There is a long path from the production of knowledge in the scientific community to its eventual appearance in the classroom (or in the Sunday newspapers). The history goes something like this. Fragments of possible 'knowledge in the making' are produced in original papers in the primary journals. Meetings at conferences expose new ideas and look for any emerging consensus on

system educational the that so jobs, by made demands knowledge and skill the that with and economy, the alters change Technological system. tional educa- the in needs new generate flow this of consequences social The knowledge. that for need the existence their by evident make and them, behind knowledge the teaching for available become resources technical These canning. or refrigeration by food of decay the preventing is example obvious an mechanisms: or ciples prin- of knowledge through than interaction technological through area an about more know may They them. 'understanding' without artefacts, of range wide a with acquaintance first-hand some have generally people ult, res- a As computing. of spread the and power, electrical of availability spread wide- the television, and radio include Examples them. behind knowledge the does than rapidly more much socially diffuse technologies Often science). computer is example recent (a knowledge of kind special own their contribute also technologies All understood. not still course, of are, some and — understood are they before centuries) (perhaps long established fully become working) metal- and smelting example, (for practices technical some But transmission. radio example, for — theories existing upon depend and use technologies Some products. their with interact people and develop Technologies ety. soci- enters knowledge which by path different, very second, a is There year-olds. 14 to thing same the teaching in difficulties same the bemoaning journals to letters write now teachers ates; undergradu- to mechanics Newtonian teaching of difficulty the of plaining com- letters wrote Maxwell century nineteenth late the In old. century a over well being despite courses university of level the below got yet not still has radiation electromagnetic of theory the generation; one in curriculum school secondary the reached DNA through inheritance of nature the tury; cen- a within sense common everyday to penetrated less or more disease of theory germ The time. of amount variable very a takes process whole The it. knows everybody since all at teaching worth thought not is it that knowledge common of matter a such become might ial mater- the ultimately, sometimes, Just ones). new some with together errors their including (often ones first the copy textbooks Other textbooks. versity uni- previous on drawing by often it, incorporate textbooks school and ulum, curric- school the for fit deemed is material the Finally, established. thus formats the follow generally texts Later audience. new the for it framing and ordering matter, subject the rework to have appear to texts first The student. the for examples and problems with replete appear, to begin textbooks point which at courses, undergraduate for suitable deemed be may material the course, due In field. the enter to wishing others of and students postgraduate of benefit the for mainly — learnable be to designed form a in time first the for it presenting of and known, is what archiving of purpose double the with possible, as framework a complete as construct which field, the in leaders by written often appear, monographs still, Later unreliable. the from reliable the sift to and relate, they how show to results, integrate to attempt journals review in articles time, some After wrong. which and right look results which CLASSROOM THE IN SCIENCE EXPLAINING

60

REWORKING KNOWLEDGE

61

is expected to prepare people for coping with such jobs. Technological change

thus helps to determine priorities for and the speed of transformation of knowledge.

Didactic transposition The transforming of knowledge from forms which are appropriate to a given scientific community to forms adapted to teaching at a given level has — in the Anglo-Saxon educational tradition — no accepted name. Being unbaptized, it seems not to exist. In other European educational cultures, it has acquired the name 'didactic transposition'.

The use of the term 'didactic' may need a gloss for the English reader, to whom it is likely to suggest 'unduly authoritarian teaching'. In a wide range of other European languages, 'didactics' refers to the careful analysis of subject matter for teaching purposes. What in England and the USA would be called 'science education' would there be called 'didactics of science'. To claim the title 'didactician' is a proud boast, not in the least an apology. Let us take a very simple example of this reworking of knowledge for teachers and learners. It is the notion, widely used in primary science, of a 'fair test'.

Faced with trying to communicate something of 'scientific method' at the primary level, primary teachers and their advisers hit on this expression of part of what is involved, and it proved so apt both for teachers and pupils that it caught on like wildfire. The idea transforms an aspect of what is done in doing science in such a way as to be memorable, intelligible and able to be put to use in the primary school. What is explained in a science lesson is a carefully versioned form of knowledge, specially adapted to be appropriate for learners in a particular context. This versioning is the product of work, often over many years, by teachers and textbook writers. The process is in many ways akin to what the popularizer of science has to do to reach a mass audience, though the social constraints differ importantly — readers of popular science do not have to sit examinations!

One obvious product of didactic transposition is the circuit board now widely used in schools to teach about simple electric circuits. Another is the use of universal indicator to teach the idea of the pH (acidity or alkalinity)

of a solution, just by associating colours of the indicator with the pH of the solution. A more complex example is the development of periodic table displays showing graphically such properties as ionic radii and ionization energies, so that various kinds of periodicity could be appreciated and compared visually. In what follows we will examine another case in detail, showing some of the transformations that have been made and how they set the frame for the act of explaining in the classroom.

part, most the For experience? everyday in itself present sound does How lines. wavy in seen be to patterns about and wavelengths, and quencies fre- vibrations, about all is It life. everyday in us to appear they as sounds with do to little have to seems story new that And sounds. about story new a of protagonists the now', and here us to 'present possible, as concrete as make to is do to trying be to seems Alan What together'. close getting all 'they're objectified: become has screen a on light of pattern mere A 7). Chapter (see is used language the visual and physical how striking is It represents. actually image the what blurring justify to advantage enough big a is this thinks he Perhaps converse. the and together' squashed more means 'higher as appears relation That tion. rela- reciprocal a having variables as wavelength and frequency with dealing avoid to image, the of appearance the on effect an saw they that fact the on capitalizes He frequency. and wavelength between relationships reciprocal the into effort of lot a put to starts now He same. the seeming, into talked be can made, be can which another for picture one substituted has Alan screen. the on graphed oscillation an at looking are they wave; a at looking not are students the But wave. a name, new a has at looked being is what And display. visual static a into transformed been has time in variation A life. real in rare is it as discussion further the in dominant as be will which variation, sinusoidal a means doubt no Alan wave' smooth nice 'a By screen. the across going that like wave smooth nice a see should you — note pure nice a Alan: get we if — see should You shapes. different — lines different OK, Student: shapes. different and lines different making by sound? of types different the display to try it does how .

.

.

so that, like them display can't oscilloscope cathode-ray The

Alan:

represented: and representation between gap the with concern his continues Alan time. in variation its of pattern the example for — it hearing from get can we than is', really it 'as sound the of more see can we since too, one good a been have would 'Yes' answer the fact in But represented. the from way long a is representation the So screen. on line bright a not is sound and screen, a on line bright a is image The a

No. Student: are? really they as them display it Can air? the through travel that waves sound real the like anything they are — screen the on see we waves sound The

Alan:

itself: sound the and screen the on represented is what between relation the about cerned con- is He light. another, to sound, medium, one from transposition a tion, visualiza- stresses He oscilloscope. cathode-ray a on displayed are they when microphone a into made sounds of patterns the students 8 Year showing Alan teacher the 7, Chapter in detail greater in discussed lesson a In is

—

—

transposition didactic a sound: Seeing 62

CLASSROOM THE IN SCIENCE EXPLAINING

REWORKING KNOWLEDGE

63

sounds are just present to us, on a par with tastes and smells. We have little sense that they involve vibration (though we do sense vibrations for loud low-pitched sounds, and we do associate some sounds with vibration as in the rumble of traffic). We have little sense that sounds travel (even an echo or a delayed thunderclap appears to be 'a sound happening a little bit late'). For most purposes, a sound seems to be heard at the instant that it is made. The region round a source of sound appears to us to be filled with its sound. We often hear round corners. But it does seem that sounds can be blocked, since we hardly hear sounds from inside closed spaces. And the region filled with sound is rather local, since we do not often hear sounds from far off. Living with technological artefacts teaches us that sounds can be recorded and played back, and that they can be sent by other means (telephone, television and radio). Experience does not tell us whether the air, which is always there, is an essential or accidental accompaniment to the possibility of making and hearing sounds. And since we have rare experience of deafness, and then mostly at second hand, being able to hear seems natural and normal,

not in need of being made accountable. What, by contrast, does the scientific story look like? Sounds are made by making vibrations. But for most sounds the vibrations are too rapid to feel as vibrations (typically from hundreds to thousands of vibrations per second). Sounds are heard by producing vibrations in bones in the ear, which set neurones firing and sending information about the vibrations to the brain. That information is subtly coded, so that we hear the presence of differently pitched sounds simultaneously (technically, the ear—brain system does Fourier analysis, unlike the eye—brain system with which we do not

'see' the different colours in the light from a source). Sounds belong to a wide class of phenomena named 'waves', which share a similar underlying theoretical analysis — the equations describing them have similar forms, and the mechanisms are analogous. Because of this, there are a common set of terms to describe any wave: • frequency (rapidity of vibration) • wavelength (distance apart in space of correspondingly excited places) • amplitude (magnitude of the maximum excitation at a point) • velocity (speed at which the excitation propagates)

These and other terms are taught because wavemotion and vibration of many kinds have turned out to be important in many parts of science and engineering. The description of sound waves contributes to a much larger agenda than it seems. But while they are generalized terms of description, however, these terms also have explanatory force. The pitch of a sound 'is nothing other than' its frequency of vibration. The loudness of a sound 'is nothing other. than' its amplitude of vibration. A wave is a travelling disturbance. It is motion in motion (or more generally change in motion). There is nothing static about it. It changes simultaneously in time and space. To visualize waves, their motion has to be frozen so that what is unchanging can be contemplated. This is done in

talking. of ways and experiences, visual activities, of variety a into reworked is equations two or one as down written be can What sound. a making of process ial mater- the in on going is what to relation their and relationships, their tion, representa- of kinds several explaining requires sound Explaining sound. about teaching of matter simple the seems what for even needed is which knowledge transforming of work the in, involved detail complex the and work of amount the stress to is analysis lengthy rather this of point The space. in out spread if look would wave the how showing one as image the 'read' to choose could we places, and times correlates itself wave the of ling travel- the since like, we if But however. wave, as it of speak to natural is it same, the exactly look can instant, an at frozen space, in wave sound a of representation a Because space. in pattern static a into time in change of tern pat- a transforms It intensity. and time both spatializes representation The oscillation. an of representation a is It wave. a not is screen the on is What oscilloscope. an to connected microphone a with seeing, were students Alan's which 4.2 Figure is It different. quite is meaning the but same, the is appearance The same. the exactly look diagrams the apart) (labelling that Note space. in point single a at oscillations other the and time in frozen wave a one tions: representa- two the illustrate 4.2 and 4.1 Figures dynamic. entirely something of representations static wholly and spatial purely now two gives This tion. direc- spatial vertical the use to is wave the in pressure in changes the ent repres- to way a page, the across spatially represented are time or space If representation. spatial a time giving by or tern, pat- spatial the see to photograph a in as time freezing by ways: main two space in point a at wave a in Oscillation 4.2

Figure

time

oscillation one for time time of moment

a

at frozen wave A 4.1

Figure

space

wavelength CLASSROOM THE IN SCIENCE EXPLAINING

64

REWORKING KNOWLEDGE

65

In Chapter 5, on demonstrations, we discuss how material things become semiotic objects — signs as well as substance. The oscilloscope here is a clear

example. Its very function is to make meaningful displays out of material things (sounds, electrical impulses) fed to it.

Explanatory icebergs: filling up atoms with electrons Didactic transformations hide knowledge at least as much as they expose it. Explanations are like the tips of icebergs, with a large amount of supporting knowledge lurking below the surface. We give an example taken from a series of lessons on the chemical periodic table, discussed later from a different point of view in Chapter 6. In this sequence, as in many textbooks, atoms are described as having layers ('shells') which may be successively 'filled up' with electrons. (Later in this chapter we will also consider 'filling up' as an example of metaphor.) The first shell can take two electrons, the second can take eight, the third either eight or eighteen and so on. Real differences between real substances such as sodium and sulphur, to everyday reason 'just how things are', are determined by these number patterns. Sodium is 'sodium' and sulphur is 'sulphur' because of the number and arrangement of electrons they possess. The reader may well have the feeling that this talk of numbers — of the magic sequence 2—8—8 or 18, is far from being a full explanation. And this feeling is entirely correct. Plainly such numbers themselves call for explanation. It may be useful to sketch what this explanation is so that one can see the hidden part of the explanatory iceberg which underlies the above very common didactic form of explanation.

The only sensible or satisfying number of electrons which could 'fill' something is, plainly, simply one. And indeed at bottom this is the simple rule underlying this whole complicated scheme. It is that only one electron can be in a given state in the same atom. All the magic numbers are combinations of the number 1. The more complex number patterns arise because the 'state' of an electron depends on the shape of its distribution in space. Further, two electrons can occupy the same spatial distribution as long as they differ in the direction of their 'spin', up or down. This lets two electrons occupy each spatial distribution. The electrons fill up the spatial distributions in order of their energy, lowest first. The first two (giving the initial 2 in the magic sequence) occupy a spherically symmetric pattern close to the nucleus of the atom. The next set of possible spatial distributions is a bit more complicated. It has one spherically symmetrical pattern, but space being three-dimensional, there are a further three asymmetrical lobed patterns oriented in three directions at right angles. Thus this set of states can be occupied by two plus three times two electrons — eight in all. The later larger numbers (18, 32) arise from yet more complex spatial patternings of states. But in the end, all these numbers follow from three simple numbers: one for the number

in survives DNA (e.g. knowledge other with together story, the of structure the into built are heredity, of material the is it that and cells, all in present is it that DNA, about facts essential Some carrier'. 'knowledge a as story the of think can we level deeper a at But willy-filly. readers, and hearers as us involves up, sets structure narrative the which resolution for need the and next, the evokes readily part one because remember to easy are Stories story. a through class 10 Year his for things enliven to seeking is Leon level one At

think. I programme fascinating a be to going it's So match. to going it's — exactly be to going it's daughter their she's if because — if see and killed were who people the of bones the to go — now? can they understand you do — now can they — is really Equinox on reveal to going she whether programmel television they're week this programme the on and — DNA the now know you — — — DNA the at looked and — yes? bone a of bit a taken they've dead she's that now — is done actually they've what So daughter. Tsar's the was really really she not or whether to as years and years and years for on went debate a was it and — right? her kill didn't they but — wasn't she so alive was she obviously — reason some — for killed' wasn't I 'No says, she since — was it think I America in woman this there's — right? — 1917 in family Tsar the all killed they said they know You [1 fascinating quite looks it it, watch should you — doing they're — er — It's that? watch to going you Are — — that? watch to going who's — Russian? a really she Russian that about programme that watch to going Who's Leon: 'Anastasia'

was

—

instance: an is Here narratives. and tales stories, in knowledge embedding is example An us. to represented is it which in or it, meet we which in form the of is reworking of kind Another knowledge. of organization 'internal' the of reworking a conceptual a of is above discussed knowledge of reworking The is It kind.

narratives and parables Stories, explicit. made be to able easily being this without structure deep such retain they that notions transposed of typical rather is It matter. of solidity the explains fermion the of concept the Deeply, once. at state same the in be can which of two no 'fermions', called particle of type the into transmuted is once at place same the in be cannot things such two which in object' 'solid of notion everyday the theory, quantum the In 'filling'. of notion common-sense seemingly the in original, of idea deep the of something retain does it But numbers. unexplained and magic by simplicity its replaces 'shells' of 'filling' of one to above account theory quantum the from transposition didactic The space. of dimensions of number the for three and tions; direc- spin of number the for two state; one occupy to able electrons of CLASSROOM THE IN SCIENCE EXPLAINING

66

REWORKING KNOWLEDGE

67

dead bodies). Conceptual connections are carried by narrative links. Not all such stories used in explanations are so dramatic — here is a much more mundane example from a Year 8 lesson about sound:

Alan: Now then I used to have terrible problems using a phone box because I worked up in Scotland in a little village. . . where the Glenfiddich whisky comes from — so it was a bit nice. And when I used to phone home there used to be a great big clock tower in the middle of the village and throughout the summer they would

have a piper standing next to the telephone boxes playing the bagpipes so you can imagine what that was like when you were trying to phone home. The fact about sound, that it can travel through solid materials, is neatly carried by the story. Telephone boxes are of their nature enclosed, and one telephones from inside, so the very structure of the story, simple as it is, embodies the idea. The telephone box should have shut out the sound but it didn't. In the next example, Leon (in a lesson about microbes) gets the Year 7 class to help create a small scenario to encapsulate some basic facts about microbes: Leon: Picture this then — because this has happened to me — might have happened to you — this is a confession for my part. If you get some

sliced bread, yeah? [1 It's OK if you live in a big family, because you're eating it all the time right? — yeah — but I don't live in a big family, right, so I get — I get some sliced bread right? And it

lasts quite a long time but usually I don't actually get to eat the last few slices — arid you've got to tell me why I don't normally eat the last few slices of my — of a sliced loaf in my house. Can you tell me why? Leon gets the answer he wants, that the bread goes mouldy, and this little episode now helps to carry the idea that unseen microbes are everywhere and in time will grow on anything which nourishes them. His students get the point. Two of them immediately recall parallel events: Student: My uncle — ages ago — he left his packed lunch box and he went

on holiday and he left it in his packed lunch box and when it was time to go all the. Leon: You lift your lid off the Tupperware and you sort of go 'ugh' Student: At our primary school you used to have these cupboards and you used to put our lunch boxes and then people used to leave

it over night and all the damp... In the next chapter, on demonstrations, we claim that stories like these have

some of the character of demonstrations. We see that knowledge can be reworked into story-like forms, not merely to add to its 'liveliness' or 'interest', and not merely to show it 'applied' to some real context, but more

'life'. with do to mainly answers getting them, to meant 'organic' word the what them asked previously had Elaine carbon. of but life of not chemistry the as form, modern its in chemistry organic of start the of parable known well- the tells Elaine, teacher, The 2. Chapter in lesson this of part earlier an discussed We chemistry. organic of study the beginning is class 11 Year A

classroom the in parable a Force: Vital of destruction The sense. derogatory a in 'ideology' term the using not are We necessary. and important both are views world broad and views, world broad capture parables Such ideology. is It ideology. avoid cannot be to ought things how of notion A misunderstanding. no however, be, there Let historians. of writing the in found be to contestation and qualification subtle the of little with confident, and unproblematic often is tone their told, are they As moral. particular a of service the in facts the bending ideology, of pieces shaped carefully are parables the that shows episodes 'well-known' these of investigation historical serious again, and Again heard). not had he fact in which (of experiment Morley Michelson— the by impressed Einstein endlessly; cannon boring by water boiling Rumford benzene; of structure the about idea Kekulé's penicillin; of discovery Fleming's telling: the shaping and driving point ideological their with often tales, such repeat regularly texts, science and teachers, Science ever. for culture Western changed idea That objects. mundane and heavenly both of motion the embrace to enough is scheme one that Earth; the circles it as Earth the towards Moon the of 'fall' the as phenomenon same the just is apple an of fall the that is It startling. more yet is insight theoretical the Newton, of case the In it. in immersed is object the when container a in water of level in rise the noting by calculated easily be can shape, in complex however object, any of volume the that is it Archimedes, of case the In thought. pure taking by discoveries make may one that is It uncongenial. too is it because perhaps telling, the in missed often is which one but interest, ideological same the serve both Curiously, trees. from fall apples that known have Newton must surely more even overflow; baths that knew Archimedes Surely obvious. seem not does drawn be to moral The puzzling. unusually are two these tales, such other many Unlike science. of folklore the of part are apple an of fall the noticing Newton or 'Eureka', of cry a with bath overflowing his from leaping Archimedes be. to ought or is science how about ideas carry parables entific Sci- be. should or are things how about idea an carry Parables parables. or tales moral in carried are science of nature the about ideas commonly, Quite

parables or tales Moral form. reworked a in knowledge, the is story The carrier. knowledge efficient and memorable a involving, an as act to fundamentally CLASSROOM THE IN SCIENCE EXPLAINING

68

REWORKING KNOWLEDGE

69

Elaine: Now originally, before about 1825 which probably seems like

the beginning of the world to you, 1825, it's not even two hundred years ago, people like you did just now thought that there was a whole class of chemical substances that were special in some way because they were concerned with living things. In

fact, they thought that these chemicals couldn't be made in a laboratory — they couldn't be made in test tubes and beakers and so forth — or in factories, although the industry wasn't organized in factories and we didn't have firms like —um— Glaxo and so on and ICI — they thought that these special chemicals

could only be made inside living things or they were the waste products of living things or the decayed products of living things. In fact, they had a theory called the Vital Force Theory. Anybody know what 'vital' really means? Student: 'Important'. Elaine: How important? Student: Major. Elaine: How major?

Student: Extremely important.

Extremely, so important that in fact Student: It's life or death. Elaine: life or death. Elaine:

Elaine:

'Vital' is really concerned with something living — OK

—

so

the

Vital Force Theory says that to put these chemicals together, you needed this mysterious Life Force. It could only be done inside living things because you needed this mysterious Life

Force. It's no good mixing things in beakers or test tubes, wouldn't work. Then along came a guy called Wöhler [1 who I guess was German, maybe Austrian, I guess he was German — and he quite accidentally made a chemical substance in the laboratory and that chemical substance was called urea. Now you must have come across that before. What's urea? Student: [Inaudible] Elaine:

It's a substance that dissolves in water that we call urine, and it's most definitely organic in the old sense. Because it's a waste product of living things, it's the way we get rid of our waste nitrogen compounds. So, he made urea, he wasn't trying to make this, he was trying to make something else and during the process he was heating it and it rearranged itself and it came out as urea. Well that upset the apple-cart a little bit didn't it? And lots of people didn't believe that he'd really made it and there was a lot of discussion but other people did think, 'Maybe there's something in this,' and after a little while, several of these organic compounds were made in laboratories. So we had to rethink — I say 'We' — I wasn't really alive in 1825, I wasn't really part of it. We had to rethink the theory. What we know

a of equivalent the have atoms in electrons that suppose would Nobody concerned. all to evident is knowledge reworking of work the Here grasp. to 'easy' and familiar made is knowledge strange some events, all At atoms. in electrons of arrangement the of pictures 'correct' make to how about equivalently, or, electrons, adding successively by atom an making gining ima- about is It atom. one any about not is analogy The 6. Chapter in ther fur- discussed is it and above, lesson 10 Year this to referred already have We like. you wherever sit to tend don't You row. next the into go you full is row first the When row. by row in go you makes she leader year the assembly into go you If [1 hall. assembly an in really chairs like it imagine to try I Ruth:

possible. as obvious and simple as seem — atoms in shells 'filling' electrons — issue crucial and subtle a make to analogy an using teacher a of example an is Here analogy. through is knowledge reworking of way obvious One

metaphor and Analogy chemistry'. 'organic called is it why and learned, be to kind this of subject a is there why explains It carbon. of chemistry the about — years several over students some for — weeks several over lessons in come to explanations the all to frame explanatory large-scale a gives parable this of use Elaine's scales. many on exist explanations that 6, Chapter in elaborated and 1 Chapter in briefly put point a to here refer usefully also may We authority. an to it ing attach- through explanation, the authorize to serves textbooks), in common 'scientists' of portraits thumbnail the in also (as person a on focus The make. to impossible thought was it substance a accident by made Wohler that is out leave would teacher no which element key the However, 'they'. not 'we' using tale, contemporary a as almost presented is It consensus. communal for need the and product, human a as science about messages has also parable The chance'. seized-upon by overthrown misapprehension 'massive — heroic and forceful is parable The right. are we and wrong was view old The please'. books your in 'write you what is This now'. know we 'what is this that And compounds. carbon of chemistry the but nothing is things living of chemistry the that is — moral reductionist and difficult more a — second The view. world theoretical whole a overturn to event crucial single a of power the is first The twofold. is here moral ideological The

compounds.' 'Carbon please. books your in that write you can So [I compounds. carbon are they is common in have all they what — plants of walls cell the makes which cellulose carbohydrate, and protein like things include we and products, decayed their and products waste their and plants, and animals with things, living with another or way some in concerned are things these of many although that is now, CLASSROOM THE IN SCIENCE EXPLAINING

70

REWORKING KNOWLEDGE

71

'year leader' enforcing the rules of their construction. In fact, the equivalent of the 'year leader' in the analogy is the student — who makes the marks representing electrons in atoms go in their assigned places. At an opposite extreme, analogy or metaphor may be so well hidden — so taken for granted — as not to seem to be analogy or metaphor at all. Clive Sutton in his book Words, Science and Learning provides a wealth of

examples. One is that of 'cell' in biology, introduced by Robert Hooke when he looked at cork through the microscope and saw tiny structures arranged like the cells of a honeycomb. Another is 'molecule' meaning 'tiny lump'. The list is endless, and for a good reason. Making new knowledge can only be done by reworking old knowledge. With help from William Whewell — who himself coined the word 'scientist' — Faraday exploited Greek words to invent the terms 'ion' (traveller) and 'electrode' (path for electricity). And he did it not to have graceful expressions, but to enforce a point of view. Faraday wanted to build right into scientific language his notion that electrolysis was a matter of particles travelling in a solution carrying with them electricity which entered at one plate and left at another. Science is not special in this respect. Everyday language is full of — some would say entirely composed of — metaphor, much of it hidden. The word 'language' itself — to do with tongues — is a case in point. So is 'metaphor' — a 'carrying across' of something, a metaphor used differently in the word 'transport'. Our concept of didactic transposition invokes the very same process. The

example of the multiple transpositions involved in the lesson on sound shows, on the one hand, the extent to which this has become 'entirely natural', and on the other the extent to which it is entirely essential.

Students thinking with analogy and metaphor In Chapter 2 we gave the example of a teacher finding and bringing to attention a possible 'misconception', that melted wax is water. And in Chapter 3 we considered the same issue from the point of view of constructing the entity 'liquid'. Here we use the same discussion to show that part of what is at issue is analogy and metaphor. The teacher is Steve; the class is from Year 7. Steve:

It's liquid?

Pretesh: Yes. Steve:

Is that a different word for water?

Pretesh: Yeah.

Yeah. It's like water in some ways isn't it. What about it is like water? [The teacher is swirling the liquid wax in a test-tubej Pretesh: It can, it, it, it can Steve:

Student: Sir, sir, sir. Pretesh: Steve:

it can move. It's runny. It's runny, yeah, it's runny like water. What else is like water? In what ways is it like water?

book Sutton's Clive in present strongly view A ideas. scientific explaining of aspects inessential but pleasing or elegant as them of think to easy too all is it so expression, literal plain by done being work' 'real the function, ative decor- mainly a with language, of 'grace-notes' as of thought wrongly but commonly are metaphor and analogy as Just accessible. more vivid, more — superficial somewhat is science learning palatable, more ideas make to in metaphor and analogy of value the that suppose to tempting is It boat. a in felt or beach the from seen be can what with analogy taken-for-granted almost an invoke to is 'waves' as sound and light both of think to Similarly, clear. immediately less is metaphor source the 'fields', as space empty through spread influences of thinking in as familiar, more and older grown when But clear. is basis analogical the of existence the computer, a like as brain the of thinking current in instance for as new, are they When ideas. new of having the and thoughts new of thinking the in crucial always are metaphor and analogy exception; an not is example The animals. of breeding domestic with analogy an by evolution of theory the to way his found Darwin way the is example famous A itself. work scientific within meanings new constructing in metaphor and analogy by played role important the above mentioned We

meanings new Constructing audible. less and visible less remain usually they though even learning, inform processes same the But 'explanations'. available publicly the provides who teacher the is it because 'teaching', on usually is book this in focus Our conceptions'. ative 'altern- called are what of many underlying time, the all on going is thing of kind this that know we And water. and wax melted between analogy the of source the are who teacher, the not students, the is it here that Notice substances. watery for and oxygen, and hydrogen of made stuff drinkable the for both service do to has 'water' word the 'liquid' Without common. in have they what catches which 'liquid' term the for motive a provide to so and water, and wax melted compare to that on capitalizes Steve 'liquid'. saying of way everyday common very a is 'watery' And runny. and clear both water, like much very is it But unwise. be would this that clear are they it, drink can they if later asks Steve When water? 'really' is wax melted think students the Do here? issue the is What liquid. a It's tube. the of out it pour Steve: could you test-tube] up picks [teacher it pour can You runny. It's runny. it's urn, like, It's Shamar: that. by mean you what explain just you Steve: Can water. like liquid a it's water, like liquid, a it's Okay, Right. liquid. It's Shamar: Steve: Shamar? water. thick like It's Student: CLASSROOM THE IN SCIENCE EXPLAINING

72

REWORKING KNOWLEDGE

73

(see p. 71) is that attention to metaphor and analogy can enliven and humanize scientific thinking for students. No doubt all these effects are present,

but we believe that the importance of analogy and metaphor in learning science is much more fundamental than this, and is similar in kind to their fundamental importance in doing science. To conclude this chapter, we will give a few further broadly sketched examples of analogies and metaphors at work. First we will discuss those which are relatively visible — overt metaphors — and then those which are better hidden — covert metaphors. Overt metaphors

An example of overt metaphor from the classroom (in Year 9) concerns the control of the hormone system, explained by the teacher using the metaphor of orchestration: Leon:

Does anyone here play a musical instrument?

Student: Yes. Leon:

Where did you play, at school or in a band?

Student: Orchestra. Leon: Anyone else? Student: Piano.

Student: I play the trombone. Leon:

What would happen if you'd all got together as a group of people and you could all play these instruments, and you just start to play?

Student: You get a racket. Leon: There would be a racket. In order to control it and to make sure

it all works and plays a tune, what do you need? Student: A team. Leon:

To work as a team. You need a team. What does an orchestra

usually have? Student: A conductor.

A conductor and what does a conductor do? Student: Controls the whole thing. Leon: Yes, a conductor controls the whole thing. So, think about it. We've said ovaries, testes, adrenal glands, thyroids, Islets of Langerhans, if they were all doing their own thing, what would the body be like? Student: A catastrophe. Leon: It would be a bit of a mess. So, you can probably half guess that there is some sort of system controlling all the glands together. Some way of making sure that all switch on and switch off at the right time. Leon:

The analogy need not be at all complicated. In the next extract the teacher, Alan, organizes a whole Year 8 lesson around the eye thought of as a camera:

When are'. things 'how of images suggest strongly but descriptions neutral not are Metaphors electrodes. and ions of 'naming' Faraday's of example our in suggested we as metaphor, the of maker the of interest specific the by — motivated — driven is invention Their arbitrary. all at not are terms Such ('monthly'). menstrual 'finger'), (Latin penis ovaries, egg, examples: obvious of set a provides reproduction Human writing. and talking of ways scientific in and terminology scientific in work at invisibly but strongly often is Metaphor work at metaphor Covert

on. so And from? come programmes its could where computer, a like is brain the If water? the to corresponds what wave, a is light If zip? the of role the plays what fastener, zip a like works DNA If whole. a as envisaged be to able package concrete complete a as comes analogy An know. to needs it everything knowing yet without work to get to thought allows which concreteness, their from derives power That power. ive imaginat- and suggestive their by way this in work metaphor and Analogy selection. natural towards driven was Darwin Thus breed?' to which from individuals selecting person the like act could evolution in 'What question, urgent the suggests immediately breeding domestic and evolution between analogy Darwin's itself. work scientific in metaphor and analogy of role the precisely is understood, be to need may more what seeing of process, this But answer. of form a suggest may analogy the And understood. or about thought be to need may what better see can student The on. so And controllers? the controls What glands? control hormones do How everything. know to ing need- without sought be can answers and asked be can questions ductive pro- which within framework a provides analogy the examples, these In it. doing of experience granted for taken the 'outside' from vision about thinking of matter difficult the in help can analogy the So image'. the at 'looking and picture' the 'taking apart splits contrast, by camera, The perceiving. and looking between come to seems Nothing seeing'. 'simply of one is vision of experience The productive. be to chance a has that two the between tension the is It eye. the like be to reworked being is camera a and camera a like be to reworked being is eye the Here

thing. of sort same the perform basically they but cleverer much is eye your in lens the So one. this like thinner become can it or powerful more and thicker become can It thickness. changes actually it because like, you if cleverer much is eye your in lens The way. same the exactly in work they but eyes your in lenses the than larger much obviously are They OK. lenses of types ent differ- of — selection a — variety a here got I've then Now good. OK please, diagram the on lens the find all you Can lens. a called something there front the towards see will you eye the of diagram the at look you if — please do to you like would I What Alan: CLASSROOM THE IN SCIENCE EXPLAINING

74

REWORKING KNOWLEDGE

75

Hooke called the small parts of living material 'cells', the word at once suggests questions about what is inside, what their walls are made of, how stuff can get in or out, and so on. Here are some examples, taken from transcripts we have cited already, of words and of ways of talking doing such suggestive work.

The first two examples concern terms from the 'scientific way of talking' which use metaphor descriptively. In the first we should note that 'transparent' is not a 'better' word for 'see-through'; this is precisely what it means (Latin: trans parare, 'appear through'). In the second we need to recall that the term 'alkali' comes from Arabic science and refers to material obtained from potash — that is, the ashes of wood used to fire pots, which was used both as a fertilizer and with fats to make soap, the latter process making essential use of the property chemists call alkalinity. . this hot wax at the moment is like water because it's seethrough. What is a better word for 'see-through'? A longer one. Student: Transparent. Teacher:

.

.

Teacher: Why do they call them alkali metals? Student: They make alkali.

Teacher: Right. When it reacts with water it's producing some sort of solution that's alkaline. The next example illustrates the rich associations a term — here 'organic' can have, and the way metaphors evoke complexes of meaning. That complex is exactly what this teacher needs to get at in order to build —

some sympathy for a now-discredited theory — the Vital Force Theory — which she wants to use to introduce the subject of organic chemistry to a class (see pp. 68—70 for more of the context). Teacher: Any other ways you've met this word 'organic'? Student: Food. Teacher: Food. Right. Does it remind you of any other words you've come across in science? Student: Organism. Teacher: Organism. Airight. What is an organism? Student: A living thing.

So far we have concentrated on 'terms', on words. But there are metaphorical ways of talking as well, which shape ways of thinking. They also work in transforming knowledge. Consider the following: Teacher: It's got a coating like rust — it's oxidized, OK? It's got a coating

on the surface where it's reacted with the air. . . Look at that. There you can see a very very bright silver surface that is practically going grey. The air is reacting with it very fast indeed. Student:

.

.

. we

put the egg on top and I think the pressure pulled it in.

meaning. of making the are they And thinking. are They difficult. it find who those for thinking to aid of kind a helpful, or decorative merely not are metaphor and analogy that plain it make section this in examples The image. another for need a make to as so mined under- being is thought of level metaphorical the Here alternative. an as serve to Sun the to planets joining string a like nothing and tracks, no are But tracks. railway were orbits the if as orbits little') ('nice predestined in') ('stay 'follow' planets that imagine to easy is It conflict. a again is second, the In lubrication. of job the do substances oily how imagine to ball-bearings, into molecules transforms teacher the first, the In there their there help

orbits? little nice those in stay they do Why themselves? by off go just they don't Why round? going them keeps actually what So way. any in Not Teacher: No. Student:

Sun? the onto joined they Are Sun? the round going keep planets the do Why Teacher:

scraping. of instead rolling just I'm because No, away? wear and hot really get they do So . Teacher: yes? bearings, ball molecule-size these on rolling just they're .

.

system: solar the about is second the and joints in lubrication about is first The big. too or small too are they because directly, see cannot we ways next The examples things about talking of analogical illustrate on. going is what of image natural the overcome to enough not is 'pressure' term the of force ical metaphor- The press. which things are pressures though even 'pulled', sure pres- the that says student the that perception this is strong So in. 'pushed' not in, 'sucked' egg the as is it see to way natural the and striking, is vacuum partial a creates and cools bottle the in vapour water as bottle a into drawn egg an of sight The thinking. and talking of ways of conflict a is there pair, this of second the In air. with reaction a get to coating the off scrape coating; the prevent to surface the cover inferences: immediate make can student the which from image an is it And eye. mind's the for image an build to face) sur- the at only solids reaches air the reaction, a of result the is rust surfaces, on is and coating a is rust surfaces, on are (coatings another one reinforce mutually air' the with 'reacting surface', the 'on 'rust', 'coating', first, the In air. the

by bottle the into pushed been had it that said we and bottle the into got we that egg hard-boiled a got we So Yes. Right. Teacher: CLASSROOM THE IN SCIENCE EXPLAINING

76

Chapter 5 DEMONSTRATION: PUTFING MEANING INTO MATFER

What is demonstration? In this chapter we consider an aspect of explanation which is essential to science, namely demonstration. There is a long tradition of demonstration in science teaching — a tradition especially strong in Germany but important everywhere. Companies manufacture and market large amounts of equipment for demonstrating everything from magnetism to microwaves; from cell preparations to colloids. 'Great demonstrators' are remembered with affection and awe; they include several famous names from the history of science such as Faraday and Tyndall. It seems obvious that demonstrations are simply a matter of 'showing nature as it is', as clearly and vividly as possible. We are going in this chapter to cast some doubt on this seemingly self-evident proposition. We will argue

that the key aspect of demonstrating is to coerce material phenomena into being meaningful. What that statement might mean will gradually become clear.

We can gain an entry into the argument by reporting a demonstration done by a teacher (Leon) in the course of a Year 8 lesson about light. Leon needs to explain that in a 'transverse wave' the wave energy travels at right angles to the oscillatory motion of the wave. We ask the reader to try to imagine the events which are happening here. Leon:

Where did the energy go? [ ] Do it this way [singles out a pupil and instructs her as follows] Hold this heavy rope. Hold it — heavy rope. Ready? Hold it tight [1 [clenches his hand in front of him to

workings, its and world the concern They demonstrations. of characteristic generally are features these qualifications few some with that believe We element imaginative irreducible and strong a had it • world the of constituents real as ones, unobservable including entities, some of vision a enforce to was function its • go?') it did way 'Which but travelling?' as energy the of think we must 'How (not as' 'being as as' 'seeing much so not emphasized talk the • now' and here us of front in 'happening as event the dramatize to made was effort every • observables of as well as (energy) unobservables of was talk the • irrelevancies accidental of shorn was 'seen' was what • conception theoretical a of service the in events was 'shown' was what • wrong go cannot demonstration the • —

—

quotes): scare in term the place to temptation the despite that, it call will we (and demonstration Leon's of features crucial some Notice explanation. in play they role the and are, demonstrations what about questions important some up opens episode little this think We if...?' happen would What rope. a have we 'Imagine say, not does Leon hypothetical all at not is It you?'). to happened 'What hard', really it do 'I'll rope', heavy this ('Hold present and actual the of entirely is language The gestures. and actions convincing the by concrete and vivid made one but fact, in not thought in demonstration a was It happen. should what envisaging in exercise imaginative an into turned been has rope a on pulse wave real a of demonstration A eyes. his with pulse' 'wave the following happen, would what 'see' to attentively rope imaginary the 'watching' hand, his of motions up-and-down real made Leon and hands, clenched strongly with rope imaginary the of ends the 'held' pupil the and He heavy. it finding of play convincing a with but student, the to rope heavy a of end the handing mimed merely Leon rope! no was there that is unusual one this makes What usual. entirely are demonstrations Such demonstration. small this in happening event an such envisage to able been have will readers Many end. other the at tug sideways a as felt be can and pulse, wave a as rope the along travels end one at shake sideways a them, between rope a hold people two When way. that student] the to himself from [gestures went energy the but down] and up [gestures way this moved I go? it did way Which go? energy the does where — energy the did where But Leon: again. up went You Student: move? I did way which So again] movement down and up the [repeats go more one it do I'll hard. really this doing I'm moved] have would hand student's the as hand his [moves moved never You you? to happened What strongly] more again, movement the [makes hard really it do I'll you? to happened What down] and up sharply hand clenched his [moves ready? you are Right, direction] the indicate to up head his [moves way this movement the do to going I'm I himself towards pulls and rope a of end other the hold —

CLASSROOM THE IN SCIENCE EXPLAINING

78

DEMONSTRATION: PUTTING MEANING INTO MATTER

79

as some scientific theory envisages them to be. And Leon's imaginary demon-

stration raises the question whether it was better for him to do it this way rather than for real. We think that in this case there are good arguments to do with the necessary role of imagination — why it was better. We conclude this introduction with an (imaginary but all too familiar) evocation of a well-known demonstration as it not meant to be experienced by students:

—

The teacher put two wires into some water in a little bowl. Froth grew on the water, and she scooped up a bit of the froth and put a match to it. The froth went bang! right there in her hand. But she wasn't hurt at all. I don't know what it was supposed to show but she must be very brave to do it. Many a student has gone away from a demonstration saying, 'I don't know what it was supposed to show, but. .'. The event is there but it lacks meaning. The student remembers what could be seen, but lacks an idea of what the events are supposed to mean. The teacher wanted to show water being .

torn apart by an electric current into hydrogen and oxygen, which then exploded, combining back into water and releasing the energy which had been supplied in tearing them apart. The student saw wires, water, froth and a bang. The demonstration failed in its effect on many counts in the list of features above, not least the imaginative, even though it 'worked'.

Vexing nature by art Francis Bacon, a contemporary of Galileo, and so writing at the time when what we now call science was being invented, gave the following advice to observers of nature: the secrets of nature reveal themselves more readily under the vexa-

tions of art than when they go their own way. Francis Bacon, The New Organon, Book One, xcviii

What he had in mind was that in the events of the natural world, the effects of various entities are entangled with one another, so that the effect of the

entity one wants to understand may be interfered with by the effects of others.

A good example from the history of science is the discovery of electrons by J. J. Thomson. In the late nineteenth century 'cathode rays', produced when electricity was discharged in gases at low pressure, were well known but their nature was a puzzle. Some thought they were a kind of immaterial radiation; others thought they were beams of charged particles. One piece

of evidence against them being beams of charged particles was that they were not deflected by an electric field — as they should be if they consist of moving charges. Thomson had the idea that the problem was that a cloud of charge from the ionised gas shielded the cathode rays from the electric field, neutralizing its effect. So he progressively reduced the gas pressure, to

some is get to likely more you're what — custard any got haven't we but custard with before this done I've said, I as — get to likely more you're What current. convection a is get should you What David: crack. to going is thing whole the that solid so is stuff that that feeling tripod] the on beaker the [places convection this got just I've is which already, times several about talked we've something is you show to want I what because burner] bunsen [adjusts gently that heat to try to going I'm Now top. on layer white a with layer, blue a urn beaker] the of base the at finger his with [circles is there here bottom the At OK? substancel the of flow no is there and side, its on beaker large [turns is it thick how see can you then, mixture, jelly-like thick a is This here. what's explain just let's But work. to it get can we if see to just gelatine, with it trying we're so custard, any have didn't we unfortunately but custard, David: be to meant it's — er — actually be to meant is this what . .

.

.

. .

work. might that experiment an doing we're that pretend we'll — we'll so work. won't it undoubtedly David: experiment an you show should I luck, of bit a with .

.

.

—

.

.

insouciance: and gloom of blend typical a with failure its anticipated show, to ready stance sub- jelly-like a in convection of demonstration a with tectonics, plate about 10 Year in teaching David, this. about clear very are Teachers intended. as vexed been not has Nature meaning. of failure a is problem The show. to meant was it what show not does demonstration the that is It fail? to it is What failing. it of nervous is demonstration a doing teacher science every course, of fact, In mind. in had we what explain now must and fail, cannot demonstrations that however, above, suggested We performance. actual in fail can both Yet 'made'. contrived, artful, essence the of are Both material. the and theoretical the between tension a involve both demonstration and ment experi- science, teaching in and doing in that is show does argument brief this what But themselves. manifest to made be cannot consequences whose cies fan- that: exactly be to out turn may fancies theoretical Our work. to bound not are Experiments recalcitrant. is nature because 'yes' is however, answer, The anywhere? getting it is show', to 'meant is it what only 'shows' stration demon- or experiment an If unsettling. is circularity of suggestion The course. of demonstrations, of true is fortiori, a same, The reveal. to built is it what reveal to built artifice, constructed and controlled carefully a be must experiment Any general. completely is course, of point, The another. see to one remove artfully to — art by nature vex to had Thomson as so effect

side-effect. a of result the became now evidence contrary be to seemed had What rays. cathode the deflect could he that found ultimately and effect, this reduce CLASSROOM THE IN SCIENCE EXPLAINING

80

DEMONSTRATION: PUTTING MEANING INTO MATTER

81

kind of nuclear custard explosion, and the whole thing stuck to the ceiling. [Students laugh] But with a bit of luck — with a bit of luck — what we should start to see — what we should see is the blue layer at the bottom starting to circulate. We should get a convection current starting, as the blue starts to rise and goes to the surface. In fact the beaker did crack and any movement of the blue layer was at best marginal. In that sense, the demonstration failed. But the class had seen, in the context of learning about the structure of the Earth, something more or less 'solid' heated and expected to move. The point of the demonstration was not to make gelatine convect, but to make a parallel between convection and processes inside the Earth. The meaning was still clear: continents move because they are carried on hot moving molten rock circulating inside the Earth, and the underlying process is one which is familiar in everyday life, not something exotic. The demonstration offered a model for thought, not a slice of life. Here is a further example of the transformation of knowledge through analogy, discussed earlier in Chapter 4. A demonstration, then, is an event in which some aspect of the material world is to be made meaningful in a particular preordained way. And this is done usually through special apparatus, chosen and constructed so as to exhibit the meaning as forcefully, clearly and unambiguously as possible.

The demonstration does not put what is to be demonstrated at risk. Yet, making something 'really happen' is, because of the feeling of risk, more forceful in its effect than just saying that it will happen. Demonstration apparatus and demonstration itself, are material objects and events composed into meaningful signs. The sign says that a particular theory is in good working order; that a given natural material process is to be understood as entities going through their expected behaviour; that things are as we say they are. At first sight it is not obvious that brute events in the material world are the kind of thing that could be made into a sign. Surely signs are parts of messages, not things which 'just happen'? Consider an air track: a hollow beam on which gliders 'float' on a cushion of air with hardly any friction. Set moving, such a glider travels an astonishing distance up and down the track, barely slowing down. It 'demonstrates' that if there are no forces, motion continues 'for ever', flatly contradicting the everyday belief

that all movement needs a cause. We choose the example because of the transparency of its artifice. The air track is clearly a heavily manufactured human artefact, not something 'natural'. Its sharp linearity is evident to the eye; the small holes are carefully contrived. And why on earth should a glider supported mysteriously on air blown through holes in a beam be taken as the representative of 'a moving thing', rather than a football or a car?

The example shows rather more clearly than most how a demonstration must be understood as matter put in service of theory. We may say that the students see demonstrations as events of a particular

kind because of the work the teacher puts into preparing them to see the events in that way. When we look at the character of that work, it is in large

burns. is) it (whatever gas this that way the in burns hydrogen that notes and match, a with alight bubbles the from gas the sets He product. alkaline an indicating colour a to lithium the near indicator the of change a by and forming bubbles by shown reaction, the to attention draws He in. lithium the drops and dish, a in water in indicator some puts he Then tarnishes. slowly it watch, they as that, way the to attention draws and surface, very sil- the displays He so. do to hard quite is it that showing knife, a with piece small a cuts He oil. in stored is lithium the that fact the to attention draws He lithium. using actions, of sequence a through goes now Tom phenomena. between differences and similarities but themselves, phenomena not ing observ- themselves find students the later that so form, table in monstration de- the of part each in observations down write to students the asks Tom actions. teacher's the of details the to down way, 'tabular' a in organized is demonstration whole the that fact in see shall We order. have and table, a to belong They metals). (alkali name group a and names, with elements, three of group a becomes here water into put stuff greyish of bits been have would What please. underlined title the Okay, whiteboard] the on Metals' 'Alkali [writes lesson today's for title the is this group, that of name the you giving by, off, start can we So okay. it, in potassium and sodium, lithium, with one the one, number called one the table] periodic the of column a to [points one that students] the to it displays and table, periodic the of copy a containing book a up [picks is today at look to going we're one the Now turn. in groups these of each at looking start, to on go to is today do to want I What table. periodic the of areas in colour to is far so done we've What Good. Tom: . .

table. periodic the in place their to reference with teacher the by ordered and chosen been have They substances. old any just not are these But each. to done is thing same the because compared, be to are substances three that is guess can we All meaning. no is there thus, Put substance. third a with same the doing then and happens; what seeing and water in substance another of quantity small a placing happens; what seeing water, in substance one of quantity small a placing involves demonstration the way, one Seen potassium. and sodium lithium, metals' 'alkali so-called three of properties the of tion demonstra- a is example The meanings. of set a into phenomena and action talk, of blend a shape carefully can teacher a how 10, Year in lesson stration demon- one of account extended an through illustrate, to now turn We —

matter with meaning-making metals: Alkali different. quite something into bangs, and froth wires, of experience an from events transforms theory The demonstration. the to prior presented theory the of product a is perception students' The theory. some of presentation a part CLASSROOM THE IN SCIENCE EXPLAINING

82

DEMONSTRATION: PUTTING MEANING INTO MATTER

83

Table 5.1 Comparison of alkali metals Element

Atomic Hardness number

Lithium Sodium Potassium

3

hard

11 19

soft very soft

Francium

87

liquid

Surface

Tarnishes

Reacts

Solution

Produces

with water

bright bright bright

slowly quickly very quickly

gently strongly violent

alkaline hydrogen alkaline hydrogen alkaline hydrogen

explodes

alkaline hydrogen

What is important is that when he comes to sodium, he repeats the same actions, in the same way, even to the point of doing each in the same place on the bench as the previous one. Here is part of what was said as Tom went through the first part of this exercise, while repeating it with sodium. Now we're going to see what happens when we cut it. [Cuts the sodium] Right, look at how soft that is. Okay, so its softer, Student: I've got harder. Tom: [Holds small piece in front of the class, with tweezers] and it's going, it's going white very very fast indeed, much quicker than Tom:

before. Student: Going what? Tom: Going white, it's oxidizing, or tarnishing much faster than the last bit. Student: Is it hard sir? Tom:

No, it's soft, it's, it's like, it's now like hard butter. If you're cutting it with knife it's about the same toughness as hard butter.

We can see the previous steps replicated. Also, we can notice the builtin comparison ('softer', 'faster', 'it's now like . .'). It is helpful at this point to show the tabular structure which, when one has watched the whole de.

monstration, emerges as the pattern underlying everything the teacher does (Table 5.1). This is a table about two things: resemblance and progressive difference. Some terms are the same and others vary. But the variations are variations on the same themes: all are cuttable but some more easily than others; all react with air and with water but some do it more rapidly than others. And these progressions match the numerical progression of atomic

number, which in the end turns out to be the deep underlying point. It is the theoretical patterns of the periodic table which order the teacher's actions — he shows the elements in strict sequence. And the tests are never

related to the character of the substances involved, but are seen to be significant simply for their consistency with the pattern in question. There is a strong focus in all the talk and in the patterned action on similarity with difference. Indeed Tom reinforces early on the point that the substances in question are theoretical entities. He questions the class about what they know

off? given was gas what Okay, alkaline. gone it's now, water Tom: the in happened has whatever So water. in was it okay, Water, Water. Students: Tom: ?] [ in indicator green Yeah, indicator. Green beforehand? there in was what Now alkaline. that's solution Tom: of sort some producing it's water with reacts it when Right, metals? alkali them call they do Why metals? I Group the for name that use they'd think you why reason a er, me, give now anyone can so H water to added is metal the when purple, indicator the turns It clear. soon will It

Tom:

coughi [Students

purple. indicator the turns it turned, it's say, can you so Okay,

Tom:

lithium. the near purple went solution indicator the that fact observable the about discussion, next the in meaning and interpretation its with happens' 'what of mingling the clearly more even see can We shape. good in are theories that means it facts; discover not does It wrong. go cannot demonstration the way a in previously, suggested we As underscored. is hydrogen makes reaction the that story the and did, it Nevertheless, .'. have. should it 'Well like, something said have would Tom fire, catch to failed had gas the if that sure rather be can We so. done has and scratch to up come to chance a given been has Nature does. gen hydro- things the of one for check we so hydrogen, expect to us leads theory that is here on going argument actual The hydrogen. is gas the that follow course of not does It hydrogen. does So fire. catches and 'pops' gas The .

sensation. choking a like it's like, It's Tom: it. smell can't I Student Tom: actually. smell horrible a quite it's quite, It's airship. big the Like Tom: fire. catches that gas a it's popping, It's pops. It Students: Tom: hydrogen? it's know you do how Right Hydrogen. 4: Student Hydrogen. 3: Student Flammable. 2: Student Flameable. 1: Student water] the on metal the to match lighted [moves look a have Let's match] a [lights is gas the what know to want we then, now Right

Tom:

seen. is what beyond well goes 'observed' is what extract, next the in see we as But, seeing'. and 'looking as on going is what represents Tom however, demonstration, the In properties. these at looking of question no is There unobservables. concerns course, of this, All elements. three these of nuclei, the in neutrons and protons of numbers the of and number, atomic the of CLASSROOM THE IN SCIENCE EXPLAINING

84

DEMONSTRATION: PU'ITING MEANING INTO MATTER

85

Students: Hydrogen. Tom:

Right, what do you get if you take some hydrogen away from water? What's left?

Student:

Oxygen.

Tom:

Oxygen yeah. OK so you'd, erm, what you've actually got left

is one H and an 0. One, water is H20, isn't it? Students: Yes. Tom:

And one of the Hs has been nicked, or stolen, by what?

Student: Burning. Tom:

By the sodium, by the, sorry, by the lithium. Okay, so the, the lithium has st— stolen one of the, erm, one part of it for itself, the OH, and it's thrown the bit that it doesn't want, the hydrogen, out, so it's come off, as a gas, and we're able to set fire to it, okay? Let's have a look at the next one.

The mixture of kinds of inference and interpretation here is complex and interesting. The inference to alkalinity from colour change is done by making the colour change mean alkalinity. The teacher is very clear that colour changes of the indicator have meanings (see the highlighted remark below). Tom:

You've seen this before, this is called universal indicator — basically it's vegetable juice. What colour, what colour is it?

Green. Students: Green. Tom: Green, okay. Now I put some, in the water. [Puts some universal indicator in the water with an eye-dropperl Student: Some? Student:

Tom:

Just so the, okay, the water's gone green, yes? Okay, so, what

that means is that the water, is neutral. Now what number is neutral on the pH scale? Can anyone remember? Student:

Seven.

Tom:

Seven, good, right. Seven is neutral. If it went an acid what colour would the water go?

Student:

Green.

Tom:

Red. Suppose it went alkaline?

Student: Blue. Tom: Blue.

Okay, so we've got red at the acid end, blue, blue or

purple at the alkali end, green in the middle. So whatever I put in there, if it changes the colour we'll be able to tell whether it's going acid or alkali, won't we?

Further support is sought, not from experiment, but from a theoretical interpretation which would make sense of the production of alkali. Here it is the argument that the pair OH — the signature of alkalis — is 'stolen' from water (HOH), leaving hydrogen to be evolved. And this interpretation is further buttressed by the way it requires the giving off of hydrogen, to occur as has just been 'shown to be the case'. Theory expects; demonstration —

(hopefully) delivers.

expectations creates He once. at things different two achieve to enough) real are (which demonstration the of aspects dangerous the on capitalizes Tom quickly]

back steps and water the in sodium the [drops Ready! sodium. so, right, All hand—. other the on er, but reactive, that be to going isn't see to going you're what that — what that hope We screen] safety the touches and out [reaches there, that's why that's very, it's mean, I but bath, the around finger], a with gesture circling a and sound buzzing [makes go just it'll times other at and dictable, unpre- very very to pieces. jar it the blew and work It's gesture] Tom: fire- [makes here up going sparks coloured know, you Coloured, in? it put he as soon As Student: pieces. to jar

the blew just it er, and now, in putting be gonna I'm lump the of size the that of piece a got chap this and off, gone know, you obviously, had stuff the and it, around crust black a a, had it and years, 10 about for us with been had that jar, glass a jar, a in this given was he and stuff, old some had we way, the by stuff new is this had, we sodium the of some and ago, years of couple a here teacher a had We story. a you tell I'll you, tell I'll screen]. safety the [of side that on you're sure Make Tom: expected. as quite out turn to have not do things that fact the at contingent; the material, the actual, the at ected dir- is demonstration the of course the in says Tom what of deal good A founded. well be might anticipations those that feeling the to credence lending anticipated, someone as

happening things of number considerable a seen had class the And relief. of sense strong a felt doubt no he should', it as 'happened had everything and thing, whole the of end the to got teacher the When it. about material and actual the of element strong a have does demonstration this Nevertheless, evidenced. be to structure theoretical the is which table the embody actions patterned the so evident', 'make to made is it theory the embodies apparatus physical as Just change. colour indicator the notes and gas, the ignites water, in it puts tarnish, and shine for it inspects it, cuts teacher the turn, in substance each For behaviour. of patterning deliberate the in is argue, we artifice, The indicator. and water matches, knife, a metal, of pellets just equipment; elaborate no is There the is metals, alkali of properties the of example this in then, Where, will. they say we because just happen to have not do — well very know students as — which produce, they events real of role the stressed also we But show'. to 'designed as artifice, as apparatus demonstration and demonstrations discussed we chapter this in Earlier us. of front in occurring actually as events its exhibit to tries and story this from starts demonstration The thing. predetermined their doing each story the in participants with story, a like built is explanation an how clearly rather see here can We CLASSROOM THE IN SCIENCE EXPLAINING

86

DEMONSTRATION:

MEANING INTO MATTER

87

of possible danger and drama, thereby achieving one of the most basic forms of difference (in the sense of Chapter 2) — namely, excitement arising from

hope mingled with fear. The students are kept watching in hope of catastrophe. But at the same time, he creates a second difference, creating a different need to explain, out of his knowledge of how to avoid danger. What follows shows his skilful manipulation of these factors, as he moves from lithium to the more reactive sodium.

Let's have a look at the next one. Student: Are you going to put that big chunk in? Tom: No, I'm not, no. This is, again, chemicals are very unpredictable, you've got to be so so careful, it's not, it's not the sort of thing you can, just mess about with. Right, sodium. Student: Sir, is it expensive, lithium? Tom: They are, they are fairly expensive, right. Next heading then, Tom:

Sodium.

Student: Who's book's this? Tom: A bit like this here would blow the room up actually [holds a sizeable lump of sodium up before the class, using tweezersl Ahh, right, what colour is it? Student: Silver-white. Tom: It's a silver-white colour when it's oxidized, or tarnished. Student: Put it all in. Tom:

No I won't. I wouldn't, I wouldn't be here tomorrow if I did. Ahh, nor would you.

The timing of this has interest, too. By choosing this moment the passage from the least reactive element to the next more reactive one, he builds the tabular comparison of reactivity into the affective as well as the cognitive structure of the demonstration. Tom checks whether they are expecting the sequence to develop, and in doing so communicates that there should be such expectations, that there is a developing structure, by asking for predictions of what may happen when the next element is tried. —

Well, what do you predict? You tell me what you think is going to happen now. Student: It's going to, catch fire, and Tom: I'm going to put potassium in there in a minute. Tom:

change the colour of the water. That's right, so let's, let's get rid of this, and er, get it back to green again. Get some new water. Student: It'll stay the same colour. Tom: Okay, so we think it's going to turn the water purple. How about, how about how violently reactive, you think it's going to be more reactive? Student: Oh yeah. Tom: How about when I cut it? Student: Softer, and it's going to be bright inside. Student: Tom:

out. turn things how by supported something also but 'made', something into drama, into turned been has table periodic the of structure the of bit A pattern. theoretical — underlying the to parallel exactly way a in patterning deep its exhibit they event the enliven merely not do These tension. emotional of development — well-judged a and actions of pattern crafted carefully a by moment given the at being into brought — realized is structure that but order, numerical in arranged elements of story unreal and desiccated a seems what by tated dic- is structure whole Its presence. physical strong a has time same the at and event theoretical conceptual, a once at is then, demonstration This water. the hits it as soon as Burns Student: up. screen safety a have to idea good a Tom: always it's why That's screen] safety the at scratches [Tom There. Where? Student: plastic. the burnt it's burned, it's Yes, [1 exploded then and [] water, the hits it as soon as burns as, burns potassium, then, right so, Erm, reaction. mild fairly a actually was that was, that Okay, Tom: yeah. Oh Student: ceiling? the on splodges green the see You there. up and there ceiling the on see can you which Tom: efforts previous of results the it?. isn't unpredictable Very giggling] and [Laughing Tom: Right. Jeez. Student: .

.

Shit. Student: explosionl small [A gas. same the it's it, for word my Take gas. same The Tom: smell? stuff that Does Student: sir? fire on it set you Did Student: shit. Oh Student: It water. the in potassium the drops [Teacher fire] catches

god. Oh Student: water.

the in this bung we when happens what see let's then, Right

Tom:

start. the at casualness calculated Tom's Notice water. in dropped when spontaneously fire catching it see they as strongly, react to prepared are dents stu- the potassium, reactive very the reaches he when this, all of result a As Softer. Softer. Harder. harder? or soft be to going is and fast, very very tarnish to going it's very, be to going it's think you So yeah. Yeah, quickly. very tarnish to going It's

Students: Student: Student: Tom: Student: Student: 88

CLASSROOM THE IN SCIENCE EXPLAINING

DEMONSTRATION: PUTTING MEANING INTO MATTER

89

Expectation and counterexpectation Demonstrations — material events pressed in service of theory — may be used

to attack or to reshape theoretical expectations. A simple example is the case of making water boil by cooling it. A flask half full of water is boiled until the remainder of the flask is full of water vapour, when it is taken off the flame and sealed. If cold water is run over the outside of the flask, the vapour condenses and the water boils under the reduced pressure. A teacher explains below how and why he uses this demonstration: I don't tell them what it's going to be before I start. I ask them to define boiling. You can never tell exactly what they're going to say. In most cases they'll say 'boiling is when you heat up a liquid and you give the

particles enough energy to become airborne'. . The key is that they associate boiling with heating, and somehow or other I'll get that out of them before we start. He wants to put in question the common-sense account of boiling, using a phenomenon which seems to defy that account. But just what needs to be .

explained? Is it, 'How can water boil when the flask is cooled?,' or is it, 'If this

is "boiling" then what is "boiling"?' We incline to think that the real question at issue is the second. The demonstration shows, not so much a surprising effect, as a fracture in understanding. Further advance will be made, not by investigating such phenomena in greater detail or variety, but by a rethinking of explanatory schemes. The explanation, in terms of vapour pressure in the liquid and in the space above it, will transform what 'boiling' is. After that explanation, the demonstration becomes something different: no longer an unexpected event but now an example of a new theoretical story. It now demonstrates what it previously put in question, namely an account of what boiling is. Not only is knowledge transformed; the demonstration is also transformed. The teacher above will also tell stories of early expeditions to Mount Everest, where the climbers found it impossible to boil eggs at the high altitude because of the low air pressure, and also of people living a mile above sea level, in Denver, Colorado, needing to use pressure cookers to cook their food. Such anecdotes serve in effect as further demonstrations. A similar function is served by film or videotape of phenomena. For example, the

teacher whom we saw explaining about alkali metals promises the class a film of the same experiments with francium. Tom: What do you think - how - what do you think rubidium would be like, in terms of its hardness? Student: It's soft, really soft. Tom: Really very soft, yes. Okay, how about if you put a bit of it in water. Would you want to be in the same room? Students: No. Tom: No, I wouldn't — no. So this one — francium? It's, I mean the

reason we don't do it, one it's violently reactive, two it's incredibly expensive. Er — you'll see a film that we'll show you.

progress. in knowledge of transformation the and entities of construction the 4, and 3 Chapters in as again, see We slower'. or faster moving molecules 'is to colder' or hotter 'feels meaning from transformation, a undergone have to also has perature' 'tern- it, do to And space. a filling bromine of one not moving, molecules of one is history explanatory Her history. explanatory an into event an from diffusion turning is she and — boiling involve not need evaporating that here — 'evaporating' and 'boiling' of notions the transforming also is She things. two doing is Elaine point. main the not is diffuse to happens matter That accountable. phenomena making of way a rehearsing is teacher the Here Elaine: good. faster, moved They faster. moved they Yeah, 2: Student Vibrating. Student: Elaine: hot? got they when doing particles the were what and Right, Student: [Inaudible] Elaine: it? with do to got temperature has — does What Temperature. temperature. The Student: gas? a into Elaine: change it did Why gas. into changed liquid, The good. No, No. Students: Elaine: evaporate? to boil to have liquid a does So, No. Students: Elaine: boil? liquid the does evaporating in and Right, gas. a Into 2: Student gas. a into turned It 1: Student

mean? evaporate does what and evaporated, liquid The evaporated. It do? liquid the did What jar. gas the in liquid a was it liquid, a had we all of first but Yeah, purple. gone all had It liquid? the — liquid the to happened what hour, one after and colour, brown dark a is Bromine jar. gas the of bottom the into bromine liquid some put You 54. page on picture The yourself. remind to pictures the at look ally actu- can you So, experiment. bromine the at looked we Then

Elaine: Student: Elaine: Student:

Elaine:

retrospect. in recalled experiment an is demonstration the time This matter. of theory molecular a of terms in understood be to are which diffusion) of (examples phenomena reviewing lesson 9 Year a from comes It evaporation. and boiling of meaning the concern to again happens which following, the knowledge transform to used being demonstration of example further A is

reaction. violent extremely an it's so and hydrogen, is which out, comes gas of puff big this there's er and explode, jar the see you away runs he as and runs, he and fallI drop a letting [mimes that like goes he and liquid, thick of sort very very a actually it's stuff, the of drip one got he's and pipette, a with man see You'll 90

CLASSROOM THE IN SCIENCE EXPLAINING

DEMONSTRATION: PUTTING MEANING INTO MATTER

91

What is involved in this last example is not counterexpectation leading to explanation, but explanations used to create expectations. The context is one of recalling several parallel demonstrations, all involving diffusion. The idea is clearly to provide them all with a uniform account. The fact that the demonstration is discussed in retrospect, as something to be recalled, suggests how it is not mere brute fact, but that it stands for something. It means that molecules move.

Meaning and material action Throughout this chapter we have been challenging the familiar sharp distinction between words and things, meanings and brute fact, theory and phenomena — 'what we say' and 'what is so'. Our purpose is not at all to suggest that everything is nothing other than just what it is said, or constructed, to be. Our idea is that meanings are closely bound up with the material world and especially with actions on it. Meanings are made from what things can

do, what can be done to them, and what they are made of. It is in looking at demonstrations that we can see most clearly how meaning and material action are closely entangled. The next example concerns not a phenomenon but an instrument. The teacher, Steve, has a microcomputer which can display a graph, and which is connected to a pressure sensor and a temperature sensor. Near the beginning Steve talks to the Year 7 group about the two sensors. Steve: I've got two things here which can make scientific measurements...

One thing we've got here is a temperature probe. This measures the temperature here [points at vicinity of probe], and it's got a little

bit of electronic stuff in here [points inside probe] and it sends signals along this wire [gestures along the wire] into this box and into the computer. So this thing is able to tell the computer how hot this water is. . . This thing [holds up the second sensor] is connected to this tube [holds up tube]. Now the only thing in the tube is air, so all there is in the tube is air, and the air is connected up to this thing up here which measures pressure.

All the talk is about what things do ('measures the temperature', 'sends signals', 'measures pressure'), and about their parts ('connected to', 'all there is in the tube is air'). What can be done to them is implied (for example, put the temperature probe in the water). The next thing Steve does is to show, again through action, what 'measuring pressure' means. He connects the pressure sensor to the computer so that its signal will move a cursor up or down on the computer screen. Steve:

.

.

. if

I take this tube out of here, at the moment it's just con-

nected to the air so it's measuring the pressure of air in this room. If I put it in my mouth, it will measure the pressure of the air in my mouth. Now, I'm going to put it in my mouth and I'm going

quite. not but there got almost it's zero for line the here line this see You line. zero the to up almost it's Well, left. moved it's across back come it's so cold, quite temperature the made just I've So 100. 50, 0, got we've bottom the along Celsius degrees got we've scale temperature the on scale temperature the because left, going It's screen]. the watches everybody and done is into goes it when happens what watch Let's —

—

—

—

—

—

[this water cold the

Steve:

Up. Omar: go? will this think you do way Which left? or right go will it think you do Or up? or down go will it think you Do water. icy the into this put to going I'm Yes? temperature? understand you do think?. you do Omar, now. water iced got I've So water. of bit a and here ice some got. I've air. the of temperature the measuring just it's and air the in sitting just It's room. the in air the of perature tem- the measuring is sensor temperature the moment, the At Steve: .

.

. .

. .

knit: closer even get meaningful the and material the proceeds, lesson the As meaning. their become actions those to responses their and objects material the on actions His them. to done be can what and do they what see to is them explain to does Steve What intertwined. fully here are meaningful the and material The be. to it like would we what by decided wholly not is behaviour whose thing material a also is sensors, temperature and pressure the and it, But communicate. to used things of class the of member paid-up fully a is computer the of screen display the And communication. of part is It event. semiotic a meaningful, a is pressure' a recording and 'Measuring

top. the at is pressure high bottom, the at Steve: is pressure low So, down. goes it suck I when so go, we There Steve: tube] the on [Sucks out. that check just Let's down. go It'll down. Go Farhan: suck? I if happen to going what's Farhan, class. the in Farhan one only There's Steve: Farhan. name's your if up hand your put Fa— called who's No, answer] give to starts [Class suck? I if happen to going what's Farhan, up. goes cross the increases, pressure, down goes it blowing, stop I as soon as And Steve:

lithe

So, again.

Up. Student: it. into blow

I

tube] the into [Blows cross. the Watch when happens what see just let's just, let's Well,

Steve:

it. tries Steve then and guesses, some make students The

right? or left go to going it Is down? or up go to going cross — move to going Is move. to going is middle the in cross the cursor the it, into blow I If sensor. pressure the into blow to

the is

92

CLASSROOM THE IN SCIENCE EXPLAINING

DEMONSTRATION: PUYFING MEANING INTO MATTER

93

The cursor goes left or right as the temperature changes, not for any physical reason but for a conventional reason, namely that this was how it was decided to make the display work. It is also a matter of convention to arrange to plot lower values to the left and higher ones to the right. Even assigning

the value zero to the temperature of ice and water is conventional. But at the same time, what the class sees is like a material phenomenon: a cross on a screen moves in response to placing a sensor in iced water. What they see differs distinctly from reading a thermometer and plotting a point on a paper graph using a pencil. Communicating and material events are now thoroughly mixed.

Steve then shows how the pressure of air in a tube increases as the temperature of the air is increased. The class are led to note how the points plotted on the screen fall on a rising line. After some time, however, the display suddenly changes all by itself:

Steve: Did you see what the computer did then? I think the computer has decided to swap things around a bit. It's still got all the same readings — it's just changed the scale a little bit. Now the computer itself has become an actor in these events. Without being asked it changed the scale and so the overall appearance of the plot. Our point here is that this kind of explanatory episode cannot be understood as meaningful talk about non-meaningful material events. The talk makes meaning out of the events, through actions, and the actions and their material consequences give meaning to the talk. To deal with this kind of data, we are obliged to give up a notion of meaning residing solely in words,

in language, and to admit that it emerges from an interplay of language, action and physical events. Where a common-sense view of language says that meaning is carried by words, we have to say that pressure sensors and computers are also objects loaded with meaning. And they get their meaning through actions. In the above example we have, however, made an easy choice of example. The demonstration was, after all, about an instrument to be used to measure and communicate. The next example, about students understanding sound through action, suggests that making meaning through material action is more general. In this example, the teacher (Leon) has just shown the Year 8 class that none of them can hear sounds of frequency (pitch) higher than about 25 000 oscillations a second. They are looking at data about other animals: Leon:

And how do we know that a dog can hear higher sounds than us? Everybody knows this one. How do we know?. . Now come on — there — there are some — what do we know about dogs — that people sometimes call them with? .

Students: Leon:

A whistle — whistle And?

—

whistle

Student 1: Whistle Student 2: They blow the whistle

Frequency. 2: Student Pitch. 1: Student Leon: low? or high it makes what voices, our with even So Higher. Students: higher. was It Student: Leon: lower? or high, note Lois's was And

sound. frequency highest the made who seeing and produce students sounds the from patterns the of troughs and peaks the counting work follows There

brilliant. that's Oh,

'Ahhhhhhhhhhhhhhhhhhhhhhhhhh' again. it do Now good. really That's brilliant. that's Oh good. really That's — me let just OK,

oscilloscope] [adjusts um

Leon:

Student: Leon: Student: Student: Leon:

Leon:

Hold

Student:

'Ahhhhhhhhhhhhhhhhhhh' note. your hold

—

Leon: note. the not laugh, that records It go? a have I Can 2: Student Student: [Laughter] 'Ehhhhh' Leon: closer. bit a Come Student:

'Ehhhhhhh'

that. like Something 'Ehhhhhh'

'Ehhhh' Like 'Ehhhh' note. any on up picture that get can we if See note. a holding just are you if happens what see — if see — note a hold to 'Ho-o-o-h' try to you want I this. Try on. go Well long? For

Leon:

Student: Leon:

Student: Leon:

Student: Leon: Leon:

Student:

note? a hold you Can not?. Or Leon: something? or 'doh' go you When note? a like do you Can 'sound'. for meaning new making into actions and bodies own students' the linking involves demonstration This oscilloscope. an on produced pattern the watch others while microphone, a into sing to students the gets later teacher The it'). hear can't you but noise made ('It's 'hearing' of meaning the changes dog a to done be can What .

.

a

it. hear can't you but noise a There's it. hear can't you but noise a made It's run they and they and

Leon: 4: Student 2: Student 1:

Student 94

CLASSROOM THE IN SCIENCE EXPLAINING

DEMONSTRATION: PUTTING MEANING INTO MATTER

95

Student 3: Frequencies. Leon:

The frequency, the number of vibrations.

Whereas in the example of the properties of alkali metals (see p. 82ff) the students witnessed a demonstration (and from behind a safety screen), here they are an integral part of it. It is their actions which are being shown to have new meanings and new possibilities. Their actions produce new effects, and new things are seen to be able to be done to their actions. And in this work, what a student does is treated on a par with what the oscilloscope does, or with what sounds do. All are events being given new meanings.

'What is demonstration, again?' Apart from our first example, all the other cases of demonstration in this chapter have been actual experiments in the classroom. Our analysis can apply, however, not only to the 'imaginary' demonstration we cited, but to other cases of invoking real events as having theoretical meaning. A prime example of this is the use of narratives about real events. Thus when (Chapter 4, p. 67) the teacher invites recall of food going mouldy, he is doing something very like a demonstration. In the same lesson the teacher (Leon) asked the class to imagine the effect of keeping one half of a cucumber in the fridge for a week, and the other half outside. He again mimed the actions to make the event seem as real as possible. Even more strikingly, the story of Alexis St. Martin's open stomach (previewed in Chapter 2 and given in full in Chapter 7) is, to all intents and purposes, a demonstration in the form of a dramatic tale. In demonstrations, the material world is made to display and comes to be seen in terms of theoretically meaningful patterns. The material is made into a carrier of meanings. But, in addition, these meanings are always in some sense at risk. The material world can always fail to seem to mean what human beings want to make it mean.

turn. in influence of clusterings four these consider now will We graphs. as such devices formal

and procedures, entities, and terms theoretical phenomena, invisible and visible including explained, being content of kind the on depend tions explana- way the matter: subject the of influence the to points fourth The • moment. the of needs perceived the to relation in adjusted and modified produced, being text, con- interactive live a in belong explanations way the interaction: ongoing the of context the in seen be to have explanations that insists third The • resources. atory explan- of stock teacher's the by and class, that with relationships vious pre- by history, personal teacher's the by affected are explanations way the teacher: the of characteristics the to attention draws these of second The • goals. short-term and long- reflecting structure a form and another one within and alongside fit explanations way the structures: explanatory of part explanations that fact the to attention draws these of first The • as occur

influences. of kinds different quite of clusters four around organized is discussion The chapter. this of subject the are explanations constrain or generate which factors The factors. different of number a on depend which answers get we now?', way this in given being explanation this is 'Why question, the ask we lesson a in moment any at If

variation of Sources

ON EXPLANATI OF DYNAMICS 6 Chapter

DYNAMICS OF EXPLANATION

97

Explanatory structures We suggested in Chapter 1 that explanations need to be thought of as fitting into a larger explanatory structure. Any given instance of an explanation may contain, and may be contained in, another explanation. Explanatory structures have recognizable shape due to the effects of the three other clus-

terings of influence. Here we have given them names which point to an organizing principle.

'Guess what teacher's thinking' We start with five 'snapshot' extracts in sequence from one Year 8 lesson. The subject is 'The Earth in Space'. The teacher is Alan. Our question is: 'What accounts for this sequence of explanations all being part of one lesson, even taking the subject of the lesson as given?' The five extracts deal, in order, with: planets in the solar system (Extract 1); the speed of light (Extract 2); freezing and evaporation of water (Extract 3); Alan warily deflecting the class from what they want to talk about (Extract 4); gravity (Extract 5). Given this variety, we can ask our question again, more from the teacher's perspective this time: what accounts for these being

the things that Alan wants the class to focus on? What is the unifying scheme here? Extract 1 Alan:

What do you call the collection of the planets that move around our Sun?

Student: [inaudible] Alan: You've got Mercury, Venus, Jupiter, Mars, Neptune, Pluto, Uranus.. . all the others. What do you call [?I You didn't put

your hand up. Is that what you were going to say? Yes? Student: Solar system. Alan: Yes, the solar system. OK? So the collection of all of the planets

that orbit around the Sun are referred to as the solar system. What is our Sun? Yes? Student: Big ball of — er — gas. Alan: OK. A big ball of gases. Good. OK.

Extract 2

can you remember why we said you sometimes see lightning, and then a little bit later we hear the thunder? What was the reason for that, again? Yes? Student: Light travels faster than sound. Alan: Because light travels much faster than sound. Can anybody just off the top of their head remember just how fast light travels?

from planets of distances the gives which textbook students' the in table a on exercise an set to is it plan: a has Alan simple. is out, turns it answer The

'gravity'. called something by place in held they're because Sun the round spinning on keep planets The

Alan:

orbits? little nice those in stay they do Why themselves? by off go just they don't Why round? going them keeps actually what So way? any —in

Alan: No. Student:

Sun the onto joined they Are Sun? the round going keep planets the do Why

Alan: 5 Extract

moment? a in points those of few a to back come we Can Alan: stage. some at on touch to thing interesting an quite be might that time have we if Right, Alan: stage. some at in them bring and them mention certainly could We Alan: are: get they answers The in. interested are they things some include will lesson the if Alan ask students Three 4 Extract

water. need we but things other need we say I As OK. Water Alan: Water. Student: Yes? about? talking just was I what with connection in live, to order in need we that something of think we Can saying. Alan: been just I've what with connection in something after I'm OK, warmth. need We Student: Yes. Alan: Air. Student: need? all we do What Earth? on life for essential is What OK. it? wouldn't ice, be would It it. of out come would nothing down upside it tip and off lid the get could you if Even solid. freeze would It Alan: over. freeze would It Student: water. of bottle a had we again and Pluto, on out were we imagine let's then. Now away. straight evaporate would It Alan: Evaporate. Student: . .

water? the to happen would What out. water some poured and whatever or flask your opened you But OK? up, burning without there stand to you allowed that on suit special very a had perhaps you that imagine Just water. some drink to trying were you and Mercury, on survive could we that imagine Let's

Alan: 3 Extract

CLASSROOM THE IN SCIENCE EXPLAINING

98

DYNAMICS OF EXPLANATION

99

the Sun, their times to orbit the Sun, their diameters and their surface temperatures. He is directing the lesson to provide ways of relating these quantities to one another. It is the data in the table — yet to be seen by the class which direct decisions about which questions, answers and explanations will be treated as relevant. Given the role of the Sun as a hot star, surface temperatures of the planets can be related to their distances from the Sun. Their orbital periods also relate to these distances. The absolute scale of the solar system (e.g. eight light-minutes from the Sun to the Earth) can also be —

appreciated.

Alan's insistence on water, as opposed to other things needed for life (Extract 3), is related to the fact that the table contains temperatures from which one can infer the state of water on a given planet, and so something about the possibility of life as it exists on Earth. The seemingly odd sequence

of Extract 3, in which the state of water on Mercury and Pluto is first discussed, followed by questions about living things' need for water, now makes

sense because this is the sequence of thought working from the table as something given. In Extract 2, Alan hints at how one could read the scale of the solar system from the table. In Extract 5 he suggests how to think about the orbiting of the planets. Alan's agenda explains his choice of topics, and why it is always he who chooses the topic. He insists on one answer where another would do: 'Can we think of something. . . in connection with what I was just talking about?' The price is that the choice of topics, their sequence, and the explanatory structure itself may seem arbitrary to the students in the class. They do not yet have access to Alan's plan. Some would be critical of this teacher's approach. But that is not here our point. The point is that what explanations are offered and what is treated as relevant are always functions of a larger structure, in this case the demands of a task which is to come.

'Sophie's question' Our second example shows how the characteristics of a single brief explanatory moment in a lesson need to be accounted for by the much larger explanatory structure within which it fits. In this case, however, it is a structure extending over a whole series of lessons. The example comes from the series of Year 10 lessons on the periodic table given by Ruth, mentioned in Chapter 4. Ruth is explaining how, given the total number of electrons in an atom of an element, one assigns different numbers of them to successive 'completed' or 'full' 'shells', ending with some number in the outermost 'shell'. This last number plays a crucial role in deciding the chemical properties of the element, groups of elements with the same number of electrons in the outer 'shell' having a family resemblance in their properties. The groups are labelled with this number (e.g. Group I elements have atoms with one electron in the outermost shell). Thus from pure counting one can predict some chemical behaviour. The extract starts with Ruth summarizing what has been said so far.

family the of so and number, group the of knowledge use to around this turns explanation The electrons. counting from predicted be can properties family chemical that is game counting this of idea The question. Sophie's by prompted explanation, her in about-turn interesting an makes Ruth

number. group the as same the be to has end the at number The Yeah. Sophie: Ruth: me? to it explain to like you Would [Confidently] Yeah. Student: Sophie? okay that Is number. group the as same the is number, Ruth: last the that so circle, the in eighteen or eight use you So Right. one. top The Student: use? you would arrangement which two these of out And numbers] of list first the [Ticks correct. is arrangement Ruth: this So VII. Group For seven. be to has number last the So Right. Seventeen. Ruth: Seventeen. Student: five?

thirty- make to need you would number what and eighteen,

ten, be would it there, eight used you if But thirty-five. you gives seven and eight twenty you gives eighteen and ten, That's

Ruth:

shell] final the in seven has pattern one Only electrons. of numbers of patterns two produce to class the gets and electrons, 35 with VII Group in bromine, of example the takes she Then answer. one only is there again where cases other takes then She shells. successive in one and eight two, placed be can which electrons, eleven has sodium that table periodic the from establishes [Ruth

got? sodium has electrons many Ruth: How Na. sodium, take we'll so Right, number. group the On is. number the what on depends It Student:

her? tell to going Who's eighteen'. or eight use to whether know, you do 'How asking, was Sophie Right, table. periodic the do to going I'm question Sophie's done I've after then and question, Sophie's over going I'm Right, later] minutes few

Ruth: [A

it. to back come definitely Ruth: I'll question. that to back come I'll you? have forgotten, You've forgotten. I've but know, I Sophie: week. last remember, you if on, earlier you for board the on it did I Ruth: today. doing we're what to back come we when that over go I'll eighteen? or eight use to when know you do how Miss, Sophie: shell. fifth the in thirty-two and shell, fourth the in Eighteen shell. third the in eighteen or Eight shell. second the in Eight already. down it got Ruth: have you of Most shell. first the in electrons two got you've So 100

CLASSROOM THE IN SCIENCE EXPLAINING

DYNAMICS OF EXPLANATION

101

properties, to find the right way to count electrons so as to place an atom in the correct group. Sophie is told to use knowledge of what should be predicted to decide how to make the prediction. Why does this happen? The answer is to be found in the large-scale explanatory context. Ruth has made, consistently and from the start, a definite choice of how to explain the periodic table. This choice is one of the possible didactic transformations which can be made, and which we analysed in Chapter 4. Instead of discussing the periodic table as a pattern of chemical properties, explained by patterns of electrons in shells, Ruth (perhaps judging that her class does not know enough about properties of chemical elements) offers the periodic table as a given scheme for predicting these properties. In these lessons, therefore, the periodic table is presented as a given representation, from which one can work out aspects of the behaviour of reality. The representation comes first, and reality second. The representation is justified, not as a summary of what elements are like, but as based on a scheme of numbers of electrons 'filling shells'. Unfortunately, this scheme, more fully explained, is subtler than Ruth wants to admit. By a quirk of the values of energies of electrons in atoms in the presence of electrons already there, the third shell may be left 'partly complete' with eight electrons or fully complete with eighteen. Since it seems too difficult to explain this to this class, she is obliged to reverse the logic of the explanation: instead of counting correctly to predict chemical properties, you use chemical properties to decide how to count correctly. Against this background, what can we say about the explanatory context? Sophie wants to know, and Ruth wants to teach her, how to get the right answer to an examination question of the form, 'What is the electron configuration of element X?' The scientific story behind that question is long and complex. Given the contingencies of the pedagogic environment, Ruth cannot (nor could any teacher) tell the whole story. Instead, the knowledge it represents has had to be transformed into another form. Mendeleev's table, with additions from which one can read off numbers of electrons, comes to

occupy pride of place. It is used as a representation, to be taken as given, from which to read off chemistry. This makes it possible for Ruth to make claims about the simplicity and logic of chemistry ('It really does help you understand chemistry'). But it leaves Ruth — and other teachers like her — with the difficulty that the basis of the representation cannot be properly explained. That basis comes out as a story about 'filling shells'. This is where Ruth used the analogy of filling chairs in rows, discussed in Chapter 4. "You

can't exactir magic it in'

In the first example above, there were issues arising from a plan hidden, initially, from the class. This plan decided what would be proper answers to be rehearsed before the questions got asked. In the second example the existence of answers shaped what questions had to be constructed. In our next

example, the explanatory structure is organized by a topic to be thought

pieces? odd little these with do you could What (molecule?). the of side one had you if bits little the with do you could what Now right? around, bits little the lying just them of lots had you imagine little the the.. up made that bits the know you but side, — other the not of. side one just mean I yeah? chemicals are there But head. your in picture of sort to hard it's this, get to try just — OK? — chemicals are There it. magic can't you No, .

. .

.

.

.

.

.

.

—

Leon: Yes. Student:

in it magic exactly can't you Because

Leon: started? Get []? first that it made whatever [] that does How Student: itself. of copies make to able just was It started. it where that's and itself, — right? — of copies make to able was and developed of sort organism little this where — right? — beginning the at been have Leon: must there enough far stuff and microbes with back go you If — microbe one got you've If Student:

Yes?

Leon:

Ijnaudiblel Student:

Leon: what? with shell. egg an Like egg. an Like Student: Leon: two. in splits it is does it all itself, with mate doesn't it no itself. with mates It Student: do actually can microbe the What OK? before, was it than now bigger it's OK, right? growing, and feeding — it's but like massively not — larger gets it so — yeah? grow to starts and food that digest and on feed to starts now it — food — of piece a on lands microbe one literally (food) of piece a on land could microbe one have You — right? — you to say to going I'm what — this amazing it's do they what is this — Palais the to go don't they — right? in it take just but amazing, sounds It said. you what do actually — incredible sounds it know I — enough strangely Nina, — actually do microbes but problem, no there's suppose I stuff? and female and male get you Could they? Could there? are ones female and male little like of sort have microbes either is choice the Now right? choose, we — that .

.

—

—

—

do We somebody. with whatever or married get usually you and — yes? one, pick You do. we what is This one'. that have I'll — something or (disco?) the — go you wherever go we know, go of sort We reproduce. we because question, good a It's you

—

that? do they do How one'. another have just can't It reproduce? microbe a does How

"I'll say,

Leon:

Student:

number. in increasing rapidly microbes about talking been have class 7 Year his and Leon, teacher, The students. from challenges sense common- to respond to tasks teacher's the of one becomes it which in about, CLASSROOM THE IN SCIENCE EXPLAINING

102

DYNAMICS OF EXPLANATION

Student: Attach them to — Leon: You could click them in — yeah?

103

you could click them in — now you've got almost like a proper (molecule?). If you could join all those little. . . now they're in a row if you join them up — you could pull the two apart and what have you got now? yeah

—

—

so

Student: Two halves. Two halves. Now if you've got more of these little bits around

Leon:

what could you now do? Student: Make a bigger one. Leon: Start all over again. So if you started off with one, and you're able to make a copy what can you do now? Make a copy from

both of them. Student: And make a copy. Leon: And you could keep on going on and on, yeah? So you see what I'm saying is, if you could get some chemicals that could copy themselves and could eventually end up with a — like a microbe.

Student: I've got a question. You know microbes attack know like. Do they' go to the toilet?

—

In contrast with Alan and Ruth, we see Leon willing to construct, off the cuff, explanations of things in which he has aroused interest: asexual reproduction and cell division, and of the origin of life in replicating molecules. The pattern continues: the last question ('Do they go to the toilet?') gets Leon to explain how the poisonous waste products of microbes can cause illnesses.

This explanatory context, shaped by the students' interests and encouraged by the teacher's behaviour, produces a number of demands on the teacher. There has to be a recognition of what it is the student may be asking. There has to be a continual process of adapting the explanation to the audience — very evident in the frequent pausing and checking. And there has to be a stock of background knowledge, both the students' and the teacher's, ready to be drawn upon, and able to be transformed in real time into forms which make sense to the audience. The matters to be explained can be unpredictable. Leon could not have known that the very profound issue, 'You can't exactly magic it in', was going to be raised. Just because of these features, it is in explanatory contexts of the kind exemplified here that we most often see what one might have supposed to be the normal form of explanation: a 'how' or 'why' question followed

by an account directed to that question. Yet more often than not we see complex interlocking patterns of explanation produced not so much by requests for explanations as by the need to produce explanations within some previously worked out framework. Does this mean that Leon's classroom proves an exception to our assumption about explanatory structures? We think not. An oversimplified comparison suggests that in Alan's classroom the structure of a pregiven object (e.g. a section of a textbook) organizes the

Freeman. W.H. Morrison, Phylis and Philip by Ten of Powers book, a to referring is Alan * you. for it get can I if see I'll picture. previous the than bigger times ten — of scale a 'On like something called it's think I Er fore. Alan: be- lines those on something seen you've So Right. you? Have class. maths our in that of picture a got We've Student: system. solar the of out right gets it until away further and further gets it and there down Earth the of circle little a see just you So OK? satellite by Earth the of taken are which photographs those then and Earth the of size the of idea some get to begin can you small quite be to appears person the that so aeroplane an from taken that's person that of photograph a shows it Then middle the in standing person a shows then It —

—

OK? field, a of

molecules at looking Ivirtually off starts it and — success any without morning this of hold get to trying was I which school in have actually we which where some- book a is there [] the start to going I'm OK? are. things large phenomenally absolutely how — is there out everything large how just morning this you to across get and try to want I

Alan:

8. Year from is class The time. the at available fact in not was resource intended the because largely visible is extract following the in happened what be) to going was (or is what is this That out. tried being are and teachers, amongst shared and developed being also are resources explanatory new time, the all Yet teachers. ence sci- other to surprise no as come would characteristics whose explanations — explanations well-practised fairly see we part, most the For classroom. the in minted newly explanations see rarely rather we that is it Thus A-level. to or year-olds 14 (say) to suited combustion, of or respiration, of circuits, electric of explanation an into notice moment's a at switch to able be will teacher experienced An levels. appropriate at things explaining of ways of variety a experience, professional their of result a as have, teachers Science

teacher The teacher. the of shape the in influences', of 'clustering second the consider to now move We science. of conceptions to related tightly principles izing organ- underlying on rest strategies pedagogic in differences and style teacher as appear may what cases, these of each In knowledge. common-sense day, every- and scientific between relations the about assumptions his is principle guiding the case, Leon's In structures. explanatory organize to used is table, periodic the representation, canonical a case Ruth's In sequence. explanatory CLASSROOM THE IN SCIENCE EXPLAINING

104

DYNAMICS OF EXPLANATION

105

How a teacher explains also has a personal histoiy of previous attempts at explaining with a variety of classes, experiencing what seems to work and what seems not to work. Alan knows of a potentially valuable resource, which he does not have to hand. His difficulty arises from the attempt to describe, in language, information which is presented visually. More often, explanations follow well-rehearsed paths, with the teacher using ways of explaining that have previously worked well. An example might be the following account of the formation of fossil fuels with a Year 7 group.

OK. Burning fossil fuels and wood puts carbon dioxide into the atmosphere. Student: Can we [inaudible]? Elaine: In a minute. How do — how are fossil fuels actually produced? Student: Over millions of years. Elaine: Over millions and millions of years. From what? Student: Dead animals. Elaine: Right, dead animals and plants. What happens to them? Student: They rot. Elaine: They rot. Where do they disintegrate, do they rot? Student: Under the ground. Elaine: Under the ground. OK. sort of bacteria are we talking about probably? Student: Oxygen [] nitrogen? Elaine:

Elaine:

Oxygen-hating bacteria. OK. So the animals when they die, over millions of years, turn into ?I

Student: Fossils. Elaine: Fossil fuels. And then when we burn them, we release energy

and we release carbon dioxide.

Elaine has made a number of distinctive choices, for example not to distinguish types of fossil fuel such as petroleum or coal and so not to distinguish plant or animal origins. For her present purpose, the broad picture may be enough. This emphasis on the recognizability and 'normality' of many explanations must not be taken too far. Like many teachers, Elaine can improvise around a fixed theme, using material that comes from the class or that she thinks of on the spur of the moment. An example comes from work on the same topic, but with Year 9. Elaine:

We're adding to the carbon dioxide in the air every time we breathe out. Something is going on in our bodies that's making carbon dioxide? Mary?

Maiy: Elaine:

Food.

It's something to do with food.

Student: [Inaudible] Elaine: Good.

Student: Photosynthesis. Elaine:

That's what the plants do.

students. of tions collec- disposed differently to points classrooms Leon's and Ruth's, Alan's, in happens what that so different, inherently are 'classes' that assumption implied an is there hand, other the On experience. of histories of result a are styles and strategies show, to attempting are we as — style pedagogic a have teachers that suggests it hand, one the On one-sided. too picture the left That structures. explanatory of characteristics the and style, and egies strat- pedagogic teacher's the of interrelation the earlier mentioned We

class the with relationship teacher's The practised. and improvised simultaneously are explanations such concerto, a in cadenzas virtuoso the Like occasion. the of needs the be to judges she what to according way varied and flexible a in them on ing draw- resources, explanatory of set substantial a with teacher a suggests us' of part little every to 'gets oxygen how of evocation vivid rather Elaine's energy. release to digested I've that food the with reacts and cell every to round all goes oxygen The shoulders. my to up back, my to round tips, finger my to down toe big my in cell every cell, brain every cell, every us, of part little every to Gets stream. blood the in bodies our round all goes oxygen The oxy- the in breathing by eaten, we've that food the from ergy en- release we where process the that's And good. Respiration, Elaine: Respiration. Student: [

res call we

that process the during dioxide carbon out breathe animals the so OK, Right, ago. while little a in breathed I oxygen some from is out breathing I'm dioxide carbon the and stream, blood my in round going still probably is in breathed just I oxygen The

Elaine:

lesson. same the in later little a following, the in improvising be to seems also Elaine intended. first at have may she than explanation deeper a improvises she mistake, a to then and question a to responding in Thus, reverse. in other the like much very is process each that out pointing deeper, even gone have might She respiration. through released is and animals, for food in incorporated becomes which atmosphere, the in dioxide carbon from carbon traps photosynthesis how explains next she lesson this In explanation. of level general more a to shift to it uses Elaine inappropriate, or wrong as 'photosynthesis' reply the rejecting of Instead

together? go they do How Elaine: together. go They Student: photosynthesis? and respiration between connection the What's think. you as funny as not it's good, hey, Elaine: Respiration. Student:

that funny, not it's Now, Elaine: laughterl [Student CLASSROOM THE IN SCIENCE EXPLAINING

106

DYNAMICS OF EXPLANATION

107

The reality is more likely that Leon's strategy, as much as Ruth's and Alan's, make possible, foster, encourage, allow the students to develop particular forms of interaction. It needs a relatively close look at microstructures of interaction to get at this. Take the example of how each teacher deals with questions. In Leon's classroom students can initiate discourse:

Student: How does a microbe reproduce? It can't just say, 'I'll have another one'. How do they do that? Leon: It's a good question... Student: How does that [1 whatever made it that first [1? Leon: Get started? Student: Yes. Because you can't exactly magic it in. Leon: No, you can't magic it.

Questions are initiated by students; they are not just admitted, they are 'taken up' seriously, and taken as part of a dialogue; so, for instance, the student's, 'Because you can't exactly magic it in', is not just a statement (rather than a question), it is a very confidently and challengingly made statement. Clearly, the members of a class will respond in particular ways to this mode. In Ruth's class the strategies are different. Students also initiate questions: Sophie: Miss, how do you know when to use eight or eighteen? Ruth: I'll go over that when we come back to what we're doing today. I did it on the board for you earlier on, if you remember, last week.

Sophie: I know, but I've forgotten. Ruth: You've forgotten, have you? I'll come back to that question. I'll definitely come back to it.

Here the teacher's strategy is to defer answering until the 'proper place' in the explanation is reached. Whereas in Leon's classroom students are involved in the developing organization of the sequence, here they are not. Here, student questions, when they are answered, are answered in terms of providing content within the structure. In Alan's classroom students tend not to initiate questions. Their answers are quite closely circumscribed by the demands of the schema which their teacher has in mind; his questions tend to have the function of making students the 'sayers' of already established content; thus, perhaps making that knowledge theirs, or securing their participation in the sequence: Alan: What is our Sun? Yes? Student: Big ball of — er — gas. Alan: OK. A big ball of gases. Good. OK.

As we saw, responses to student initiated questions look like this: Alan: Right, if we have time that might be quite an interesting thing to touch on at some stage.

ways subtler involves also but questioning, direct involve may This feedback. provoke to and signals for look to then has teacher The can't. they times some- and — doubts or problems have they if say necessarily don't Students

all for explanation some, for Problem them. of some describe we section this In manage. can and encourages teacher the action inter- of kind the on depend will needed is which explanation of kind the and done, is explaining how affect All on. so and through, something think to pupils getting misapprehension; a correcting ideas; pupils' eliciting tion; informa- new giving issue; an crystallizing point; a clarifying issue; new a up opening include: tasks Other ideas. those with something does teacher the when phases other and ideas, produce pupils when phases have may lesson The word. a explaining be may it — aside brief a be may There continuously. changes hand in job the of nature the lesson, a of course the During manipulate. and control to and provoke or stimulate to time same the at has teacher the something is and out, turn explanations way the for crucial then is interaction ongoing the of nature The explanation. an in this incorporate to and know, they what out draw to attempting class, the with interaction in constructed often thus are Explanations all. for and once them present to attempting by than rather repetition by established be to seem often Explanations them. correcting and elaborating and previously given tions explana- partial over going of rehearsal, of nature the have classroom ence sci- the in explanations many is, That account. correct and complete more a out fill to answers to adding and rewording correcting, teacher the with answer, and question of form some by conducted are explanations often, Very around'. time first explanation 'complete of examples see to rare is It teacher. the by used strategies the by constrained are students how at looking means also It do. students what on depends behaviour teacher's the how at looking means This evolves. lesson a as produce students which feedback immediate of effect the especially chosen, being resources explanatory particular to leads classroom, the of interaction dynamic the in what, at look we section this In

interaction ongoing The interaction. ongoing the influences, of clustering third our consider to come we this With do. to meant is and is explanation an thinks teacher a what into insight an us allows it focus, our for importantly and positions, dis- social and personal their of aspects on stance, epistemological teacher's a on but sequences, explanatory of kinds different of generation the on only not light throws interaction classroom of aspect this general, In bay. at questions student keeps sequence explanatory pre-existing framed, strongly a speaking, Broadly CLASSROOM THE IN SCIENCE EXPLAINING

108

DYNAMICS OF EXPLANATION

109

of reading students' behaviour in the light of one's knowledge of them. In Chapter 2, we described a teacher — Steve finding a student who thought that the melted wax was water (a not uncommon idea). Here is how Steve begins to get his Year 7 class as a whole to hear what each other thinks has happened. —

It melted into water? So, Daniel, have you got, in your tube at the moment, have you got some wak—, have you got some

Steve:

water? Yes, sir.

Daniel: Steve:

There's water in the tube, says Daniel. Put your hand up if you agree with Daniel that there is some water in the tube.

Student:

No.

Steve:

Now, if you agree with Daniel that there is water in the tube, put your hand up. Okay, so some people think there may be

water in the tube. Kersuma, why do you think that there's water in the tube? Kersuma: I don't think so. Steve: You don't think there's water in the tube. Okay, right, why do you think Daniel thinks that there is water in the tube? Kersuma: Because it looks like water.

This discussion of what is in the tube opens up a space for anybody who might agree with Daniel that melted wax is water to join in, and Steve creates a chance to explain not merely that an idea is wrong, but that there may be a good reason why people get it wrong. Feedback from one student has been converted into explanatory feedback for all.

Terms and meanings In the same lesson Steve talks to a small group about how they would describe 'the stuff inside the test tube'. They use the rather vivid and wellmotivated term 'see-through', a meaning directly linked to action. Steve would like them to replace it by 'transparent'. Steve's justification for preferring one term to the other is that 'transparent' is 'scientific' — which of course it is by custom, not by merit. Steve:

In what ways is it similar to water?

Student: It's see-through. Steve: It's see-through. What's another word for see-through? Another

word for see-through. We want a scientific word for seethrough?. . . we'll come up with it later. . . Apart from being see-through, what about its, has it got the same colour as water? Student: Yes. Steve:

What colour's that? Has it got a colour?

Student: No.

So it's colour Student: It's clear. Steve:

?j

Ruth: table. Periodic table. periodic fewl [A Students: from? number the tell you can table what And elements. Ruth: different and. particles of. elements different got They've .

.

.

.

[Inaudiblel

groups? about different what's know you Do particles? those of numbers different have they why know you Do particles. those of numbers different have They [Inaudible]

different? they are Why Yes. fewl [A

Student:

Ruth: Student: Ruth: Student:

Ruth: different? atoms all are And Neutrons. Neutrons. Student: Ruth: and electrons Protons ?I [

[Inaudiblel

Student:

?j [ specific three of made were atoms that Ruth: said we 10 Year in course the of beginning the at and Atoms Atoms. Student: about? know you that ticles par- the of names the are What ideas. your expand to want I now particles on work of amount small a did you 9 Year in Now Ruth:

work. to going is it sure make to needs she but table the introduce to wants she how of idea an has She class. 10 Year a to table periodic the introducing before particles on 9 Year from ideas revises Ruth example, next our In already. know students what to tuned are explanations that so start, to best is it where of ment assess- 'on-line' an as serve also may questions The questions. ask to is so do to way One topic. new a of nature the signalling at looked we 2 Chapter In

know you what asking by do we'll what Telling used. be should words these contexts what in and when use, through explains, implicitly rehearsal of process This cases. different in words learned newly the using start they and whole a as class the to recapitulated is this on Later see-through'. for word 'a indeed is Transparent through'. 'appear is, that parare, trans is transparent of root Latin the that 4 Chapter in metaphor discussing in remarked We

see-through. for word a That's transparent. It's see-through. and colourless It's colourless. It's

Steve:

[Inaudible] Student:

colourless. It's Colourless.

?] [

colour

[

colour it's So,

Steve:

No. Student:

colour? a got it has this, what's So Yeah? colour. a got it's but clear, Lucozade's yeah? it, couldn't see-through, mean could clear well oh, clear, It's

Steve:

CLASSROOM THE IN SCIENCE EXPLAINING

110

DYNAMICS OF EXPLANATION

111

Such exchanges tell the class that they will be working on the periodic table, and that protons, electrons and neutrons will be involved. And they tell Ruth where she has to start.

Collecting and using ideas Teachers often set themselves the goal of weaving explanations out of ideas and contributions from the class, and furthermore to give most students a chance of contributing. This is not necessarily easy. In the following extract

from a Year 7 lesson, Leon has to get students to listen carefully to each other: Nina:

I wrote 'microbes are possibly the smallest, possibly, the smallest cells, cells I think, which you can only see through a microscope'.

Leon:

Alright who agrees with that? Who agrees that you need a microscope to see them?

Students: Yeah. Leon:

Sally: Leon:

OK so but we did say an interess—, you did say an important thing about them, we just said they're living things. What did she say that was extra to that? They live in human bodies. No, she didn't, Sally. Say it again and see if you can spot it. Listen.

Nina: Leon: Sally:

Microbes are something that are lit—, tiny living cells in the human body. Did you spot it? Cells.

Leon selects part of what Nina wrote about microbes ('that you can only see microbes through a microscope') and follows that up with the rest of the class. However, she has also mentioned other relevant information ('that they are small cells') which he must not forget to address. Many explanations require a complex of ideas to be collected. By listening not just to the ways contributions are phrased but also by paying attention to what is missing, the teacher can get an indication of which points need to be reinforced or which may not have been properly understood. An insistence on involving students in at least the partial production of explanations obviously leads to trouble if they do not know enough of what the teacher wants them to contribute. In such cases teachers often resort to verbal or intonational clues, for example leaving words unfinished, leaving sentences incomplete but with strong structural hints as to the required filler, and by playing with stress and intonation. We saw an example earlier in this chapter: Elaine:

So the animals when they die, over millions of years, turn into {?]

way the in both it does He class. 7 Year his for substantial and real fields magnetic making into effort considerable puts (Alan) teacher the below, discussed lesson the In space? that in curious anything is there that mean that does but space, that in happen things curious sure, be To space. empty like remarkably looks field' magnetic 'a called hear they what difficulty; ous analog- an have Pupils fiction. mathematical a are fields magnetic that view: opposite the held opinion of body substantial a time, the At substance. ial mater- any as real as were fields magnetic that speculate to on went Faraday 3243) para Researches: Experimental Faraday, (Michael force of lines the of character physical the respecting speculations few a upon enter and time, a for reasoning of line strict the leave to about now am I force. magnetic of lines the defining and describing in engaged been recently have I .

.

.

question: real a is this that clear was Faraday Michael occur? effects magnetic where places about talking of way a just it is Or real? something field magnetic a Is

intangible the Explaining things. intangible ently inher- explaining about is here example The book. the in elsewhere found be to others indicate briefly then and here example one give will We are. they what and work things how on depends something do to How account. the frame and organize to help which terms new introducing by accompanied often is works something how of account An are. things how of understanding an by motivated are but tions, conven- pure ever if rarely are Conventions explained. be to thing of kinds different for explanation of forms of cases pure find however, not, do We conventions.

and terms explaining from differ Both phenomenon. a explaining as same the not is something do to how Explaining graph. a as display its of form artificial and conventional the and wave sound a of action invisible the both explaining involves oscilloscope ray cathode a on sound a of display the of meaning the Explaining molecules. of motion intangible and invisible the involves evaporation explaining but touched, or seen be principle in cannot that nothing needs work skeleton the in joints how Explaining explained. be to is what on depends obviously needed is explanation of kind What

explained be to matter subject The explained. be to matter subject the of influence the interest, of clusterings our of fourth the discuss to come now we this With fuels. Fossil Elaine: Fossils. Student: CLASSROOM THE IN SCIENCE EXPLAINING

112

DYNAMICS OF EXPLANATION

113

he talks, through the way he acts, and through the examples he brings into focus. Here are all three at work, in a discussion which follows Alan having reminded the class that he previously got them to feel how hard it was to pull a piece of iron off of a large magnet:

Now then, I don't suppose this is the sort of place that you'd go and hang out at weekends, but how many of you have been to scrap yards before? You may have seen as cars — as the old crushed cars are being moved around the scrap yard Student: Oh yeah — that big — like that big round magnet — it goes and drops on the thing and then it's crushed into a square [student Alan:

gestures a large round object in mid air] Alan:

OK, brilliant. Some of the scrap yards have on the bottom of their cranes a great big magnet [Alan holds his hands out wide].

So all the crane driver does, is move the magnet over the top of a car, lowers it and the car goes 'boing', sticks to the magnet, and they can lift the magnet up on the end of the crane and up comes the car as well, stuck to the magnet [Alan mimes all this with vertical movements of his two hands]. And then they can move it across — if it's going in one of those crushers — those car crushers [crushing gesture]. Brilliant. If this magnet is strong enough to lift a car, do you imagine that you have half a dozen people going like that [Alan braces a foot against a table and mimes a struggle to pull something towards himl trying to pull the

car back off the magnet when they've finished?

One thing Alan is doing is opening up the possibility that it must be possible to switch magnets on and off (the lesson is about electromagnets). But another thing he is doing, through the very concrete and physical character of the talk, through his bodily gesture, and through the choice of example of lifting something very heavy, is to suggest the real physicality of magnetic effects. 'What's big and strong must be real,' goes the rhetoric. Alan then reminds the class of practical work they have just done looking at magnetic fields visualized using iron filings:

One or two of you got as far as sprinkling iron filings over a sheet of paper under which there was a bar magnet. OK, what did you see if you did that? Student: There was a — the iron filings — some of them — stuck to the bar magnet and you saw the shape of the bar magnet, and they like made circle patterns round the outside. Alan: OK brilliant, so in other words a little bit like this pattern up Alan:

here [points to a photograph of filing patterns in a book he holds up].

The curved nature of the filing patterns was salient for the student. For Faraday, that was reason enough to think the field real: It appears to me, that the outer forces at the poles can only have relation to one another by curved lines of force through the surrounding space;

the at found be to

is

imagination theoretical of lot a involve to planations

ex- for calls matter subject the of nature the which in example Another

examples Other talking. of way his use to begin themselves students the to, them telling his Without end. this to together work all class, the for imagined and real activities of choice his and powers impressive on focus his body, his language, through work Alan's and entity, new a of tion construc- the plainly very is here issue explanatory The accord. own its of acts which present something a to happens, something where space empty from students, these for transformed, being of process in are fields Magnetic

they? don't up, stick to start they pole the reach they When Student: Yes? poles? the at do lines field the what To lines? field to relation in is, that why see you can OK, strangely? rather behave would compass your mag— your south magnetic the or north magnetic the over directly Alan: standing were you if that saying were we remember you Can him: answers who student the for and Alan for both clauses, in role agent active the play to start lines field field, magnetic Earth's the about talking later, little A act. to able agents unseen as story Alan's in appear to started have lines' field 'magnetic how also Notice 'stick'. can filings iron which to 'there' something are lines field the that presumes that account an shapes; field reveal filings how of account reputable than less a offers he that reality, of sense this to add to patterns filings iron of effect visual the using in he is interested So real. the of stone touch- the touch making students, in Thomas' 'Doubting the to appeals and existence, material have fields magnetic that presupposes language Alan's OK? them, see to you enables that And are. lines field magnetic the where — is field netic mag- the where points the to stick filings iron the magnet a over filings iron sprinkle you if However, it. see can't you but space that in there something is there tell can you so apart]... then and they? don't apart, other each push together pushed hands to try and interact they same the poles two have you if because there, be must lines field magnetic those tell can you together, magnets two hold you if but lines, field magnetic these see can't You Alan: .

fields: of existence material the for concern a involves about on is he what that scious con- plainly is Alan there'. 'out being as fields evoking implicitly patterns, these of photographs at looking to over given is lesson Alan's of part A

3258) para Researches: Experimental Faraday, (Michael space. intermediate that in existence physical of conditions the without force of lines curved conceive cannot I and CLASSROOM THE IN SCIENCE EXPLAINING

114

DYNAMICS OF EXPLANATION

115

end of Chapter 7, in a lesson on the movement of the continents. There the issue is, rather than intangibility, the remoteness from any possible experience of what is being used in the explanation. As in the case of magnetic fields above, the teacher there uses a large amount of gesture and body language to evoke the events his explanation requires. A rather different pair of examples is that of teaching density (Chapter 3)

and teaching graphs using a computer (Chapter 5). In both these cases, much of the work goes into making abstractions — and in the case of graphs, conventions too — seem very concrete.

Finally, earlier in this chapter and also in Chapter 4, we discussed work on the chemical periodic table. This subject matter is a grand classification scheme, which demands a rather complex approach to explanation. Is it to be treated as an extensive classification of empirical facts about elements? Or is it to be treated as the product of a theory of the structure of atoms, which predicts patterns of facts about elements? Is it to be shown historically as built up piece by piece though nevertheless under a large guiding vision, or is it to be provided as something 'given', a familiar classificatory tool of chemists to be used before being understood? Thus in this case, the nature of the subject matter does not determine the form of explanation, but poses difficult problems for it to solve.

narrative. of devices the of some using subplots, and plot with story, a like as offered is explanation an tales': of teller 'The class. the from ideas reshaping and collecting teacher's the through at arrived are explanations together': through it think 'Let's

• •

include: observations, our from taken 'styles', such of examples significant Some angle. particular a from explanation, of job the approaching consistently of way a more is It habitual. become could one though teacher, a of property personal a as of thought be to not is tion explana- of 'style' A explanation. of 'styles' of number a identify will We them. sustain to deployed be to have skills what and used, are strategies what lies, emphasis the where together, put are things how on be now will focus The performances. complete these at look to as so transcripts, our of pieces longer somewhat use we this, do To performance. complete a in together come things these all how show will we chapter this In time. one the at all these, of all of performance mentation, imple- deployment, simultaneous the on rest explanations course of But out. turn explanations how on influences contextual important of number a at looked we 6 Chapter In chapters. separate in each matter, on meaning of ing impos- the and knowledge of transformation the entities, of construction the 'difference', of production the explanation: of components necessary the on focused we So description'. of 'language our explanations, describing for work frame- our of components the exemplified and out set we 5 to 2 Chapters In

performances Integrating

EXPLAINING OF 'STYLES' 7 Chapter

'STYLES' OF EXPLAINING

117

• 'Say it my way': explanatory forms of words are laid out by the teacher and practised by the class. • 'See it my way': starting from a given scientific theory, facts and phenomena are rationalized in terms of that theory.

Thus in this chapter we present a rough taxonomy of some ways in which explaining can be done, and discuss the consequences of each, for what might be achieved and for how it positions pupils with respect to knowledge.

'Let's think it through together' One way to achieve explanations is by the teacher collecting and shaping ideas offered by students. Clearly, students' contributions are crucial: they are the actual material out of which explanations are going to be carved. They also, of course, provide the ongoing interaction which the teacher has to handle — something we discussed in Chapter 6. Thus this way of working towards an explanation places great demands on the teacher's skill. The teacher has to start students off, to stimulate further contributions, to feed in additional ideas, and to make clear what status is being given to students' they being welcomed, being clarified or modified, or are they now being made part of the final account? This involves continuous movements between, for example, opening up opportunities for contributions, and framing and 'making official' material which has been offered. Our example, previewed in Chapter 1, is a Year 10 lesson about skeletal joints. The fact that joints are places where bones move against each other has already been established in previous lessons. The lesson as a whole starts with a test, proceeds to discuss the design of a good joint, and then considers how to categorize different types of joint. We will focus here on the second stage, in which the teacher — Leon gets the class to put together a picture of what ought to go into an ideal joint. His initial questions suggest both the problem — the wearing away of bones — and establish the exploratory tone of what is to come. By starting from a rather wide definition of a joint (two bone surfaces which move against each other), and asking in general what can go wrong with them, he opens up a wide range of possibilities for thinking. ideas — are

—

Leon:

Okay [} Let's just talk about it in— first of all the principle of the

joints. What is the problem if you've got two bones that you want to move against each other — what's goin—, what's the — what's going to be the big imagine how many times

problem at the end where the? —

Student: They'll wear away. you must move your elbow, yeah? So write it down. Okay? [Starts dictation pace and intonation] Where [I two [1 bone [1 surfaces

Leon:

[I where two bone surfaces [] move [] against [1 each other II] the danger is [I they will wear away [stops dictating] . . it's .

[gestures]. that doing be weight'd your moving, be weight'd your But Student: Leon: oil. Like it. rubbing 'em stop They Student: together] talking [All Student: Leon: though? do fluids would what of, sort Some yeah. fluids, like Fluids, Student: they... but Yeah, Student: thing? plastic like, Leon: this, on rubbing they're other each on rubbing of instead So other. each hitting them stop It'd Student: Leon: ? on— rubbing of instead do, disc the would what And something. or disc a 'em, between sheet, flat a No, Student: band. elastic an Perhaps Student: know. I Student: Student:

Leon:

Yes?

Emma:

[Inaudible] it. isn't rough That's like, be that'd no, No, Tissues. sheet? of sort what Yeah it. between something of sheet a Put

Leon:

Student: Student: Leon:

Emma:

away? wearing the stop we can how Emma, away? Leon: wearing the stop we can How away. wearing the stop and try Let's use. future for vocabulary and remembering', for 'knowledge now is It knowledge'. 'textbook communal into turned been has students some of idea' good sible 'pos- a ago moment a was What notebooks. their in insertion for class the to back it dictate to deciding by status new lubricated) be must joints that (namely reach they that idea the gives He gear. changes Leon conclusion, possible a to brought and collected been have ideas once But, elaborated. and up picked are mechanisms, familiar more to it comparing by joint a of anatomy the in involved is what envisage them help which suggest, they Analogies up. followed are ideas students' of Consequences entity). this of potentials (the it to done have or do can joint a what around questioning of means by done often is This students. the by presented ideas out teasing and refocusing, rephrasing, skilfully teacher the with proceeds lesson The it? reduce to de— to do, you can what something, away, wearing the Stop think? you do what Charlene Yeah. they? aren't away, rub up- rub gonna they're hard they're if but hard, be gotta yeah, heavy, and big we're like, know, you 'cause, order, in hard be to got they've away, wear gonna they're it, round get we can how surely, it, round get we can how Charlene — we do how — How away? wear they'll or they, don't hard be to have They yeah. obvious, .

.

CLASSROOM THE IN SCIENCE EXPLAINING

118

'STYLES' OF EXPLAINING

Leon:

119

Like oil?

Student: Like oil, like they show it in the car advert. Leon: In a car, what, what does the, what does the oil do in the car, what's it for? Student: Lubricate the car. Leon: So in the car, think about it, your hard things are rubbing against

each other, but if you put oil in, a tiny thin layer, a bit like molecule-like ball bearings, yeah, in-between the two, so instead of rubbing against each other, what, they're just rolling on these

molecule size ball bearings yes. So do they get really hot and wear away? No, because they're just rolling instead of scraping. So what could you have in a joint? Student: Oil.

Some sort of oil stuff. So let's write it down, right. So this is like things we could do. Have some, write it down [starts speaking with dictation speed and intonation] we could have something like oil [ we could have something like oil to lubricate yeah we could have something like oil to lubricate [1 Student: How do you spell that? Leon:

Leon:

L U B R I C AT E [dictates again] to lubricate the joints [1 we could

have something like oil [Ito lubricate the joint [stops dictating] [I Okay, that'll do, so that would make the movement a little smoother wouldn't it?

Further problems, arising naturally as an outcome of the proposed solution for the original problem at hand, are often suggested by the teacher, though students are encouraged to have a go. But these suggestions are always made to appear to arise naturally from the discussion; as consequences of what has just been proposed. In this way the discussion, while skilfully led by the teacher, has a feeling of continuity and of dialogue. Here is Leon introducing a difficulty with the idea of 'oily stuff': Leon:

Student:

Excuse me, how do you stop all that oil stuff just spilling out? Put something round it.

Students: [Several speak at once] Leon:

So like another layer around the whole thing to keep the oily stuff in. Like seal it or something.

Student:

Yes, seal it. OK right then, then we could have — er — and it has to be like a bit flexible [] a flexible seal — should I saj' seal or cover

Leon:

or what? Student:

Cover.

Leon:

[Slowly with emphasis] Flexible cover around the whole joint [I to keep the oily fluid in — to keep the oily fluid in. []We're well on the way to making a reasonable joint at the moment.

Leon has to decide what to follow up and what to skip, without, however, dismissing contributions in a way which will inhibit students from

1. Chapter in earthworm the for effecting David saw we transformation drastic a fluids; and walls tubes, of structure a becomes body the of inside The structures. molecular complicated as re-imagined be will turn in these and fat, and protein substances generic the become will butter and steak Familiar body. the leaves and enters it as it to happens what and is, food what rethink to students get to is do to has David things the Amongst

about. talking we're that bits various the about stories, little you tell to going I'm bits, these through going we're as you, tell me let Now David: knowledge. of structures essential carry to stories use to is chooses David strategy The sense. make to order in others the needs Each interlocking. are — food to happens what organs, of tures struc- and functions the — ideas new the all Furthermore, ways. novel quite in themselves, body the of parts the at so and body, the in on goes what at looking involves it process, biological a as But process. everyday familiar entirely an level one at is digestion 3, Chapter in noted we As achieve. to things several has (David) teacher The class. 10 Year mixed-ability a with system, digestive the and digestion about lesson a is example Our along. students carry to narrative of form seductive the uses tales' of 'teller The

tales' of teller 'The joint. perfect a did I Wednesday on class in because 'me', say can you dinner?' Sunday doing 'Who's says mum your when So joint. perfect a done actually We've joint. perfect a built actually we've but — it did we how know don't I mean I — actually we've So Leon: achieved. been has what underline to joke punning a self him- allows he that worked, has strategy his way the with Leon is pleased So identified. been have joint a of features essential the all until continues This or—

nick or

break might It tube? the to happen might what joint the bend you when - it about think - in coming tube a had you if but Leon: in coming tube a either there in get somehow to need You tube. a need we there in getting of how some need We Student: objection: common-sense equally an offers Leon oil. more in feed to tube a suggests student a car, a with joint the Comparing out. seep might stuff' 'oily the that out points Leon example, For fit. might they if see to mechanisms and entities known various with mentally playing generally and questions, if?' 'what asking sequences, con- imagining ideas, out trying involves It work. metaphorical much through done is together' through it 'thinking of task the Indeed seal). (oil, phors meta- as offered are contributions students' the of Many ?'). say. I ('should them to back dictate to what class the asking Leon Notice others. making —

—

.

.

CLASSROOM THE IN SCIENCE EXPLAINING

120

'STYLES' OF EXPLAINING

121

David: This gut, the hole that goes through — the gut, is a hole going through the middle of the animal, and in the same way the tube that goes through you — starts at the mouth and ends with the anus — is just a hole going through the middle. Now you're putting food into this hole, right, and the earthworm is putting food into this hole. Somehow the food has got to get out of the hole and into the worm. Now, these bits here, the — the leaves and —and all the other bits

that the earthworm's eating, and all the bits you're eating, are made up of proteins and fats and carbohydrates and so on. The problem is that the molecules, the molecules that make up the food are co—, are long and complicated. For example, we said that. . . if you look at a starch molecule for example, which is what you get in potatoes, and what you get in — in pasta, and what you get in starch food, is made up of more than twentyfour bits, joined together like this, and the walls of this tube, okay, is like a piece of netting — is like a piece of netting, okay, these long tubes — sorry, these long molecules — are so big that

they won't fit through the net to get to blood on the other side.. . The food has to get out of the tube, through the wall of the gut, into the blood circuit and be taken around the body, okay. But these molecules are so big that they won't fit through. So what the body has to do is to break them down into small bits break them down into small bits.. so that we finish up with small simple little molecules and the small simple little molecules

—

.

can go though the tube, through the wall of the gut into the blood and be then taken off to your cells and your muscles so the food can actually be used, yes?

What David has done is to strip digestion down to the barest essentials: a tube through which food goes and in which it must be broken down. This provides a theoretical backbone, so to speak, which will — as he tells the stories which follow — hold the argument together. Further, the narrative form can, as we pointed out in Chapter 4, 'carry' knowledge in the very structure of the story and in its use of analogy and metaphor (as in 'netting' above).

In his first story, David, having established the crucial role of the stomach in digesting protein, is about to make sure this specific function is not forgotten. He does so through a surprising suggestion:

David: Most of the food that gets digested in your stomach is protein, so the meat and fish and that kind of stuff gets digested in your stomach. But would you believe that you can actually survive without your stomach?

The story which he is about to tell does several jobs at the same time. It functions as evidence. It is highly memorable, providing a ready reminder of

muscle new get I muscle a damage I if cells, skin new get I skin — the damage I if happen, should what that's cells new make to divide cells other but dies, cell the then yourself, cut you if know, you — cells new make to dividing, just of instead and mad, goes of sort reason, some for cell, one just cell, a where is David: Cysts. Student: is cancer what see let's all, of first well, Oh, — way best the ways, three in cancers cure can you Well, ways. three in cancers cure can you Well, do? you can what case, this in umm, stomach, the of cancer got you've if Now, David:

information. extra provide to off break to opts here David But stomach. Wayne's of removal surgical the about be to going is story The else. something explaining for space make to decide may teacher the Or contributions. with or questions with either in, join students often how on depending down slowed or up speeded be may It vary. may pace The level. in changes and asides many with plots, complicated of track keeping involves often storytelling through Explaining stomach. the of cancer was got Wayne John which cancer the and cancer, of died eventually day, that set film that on working was who person single every and cancers, causes ally eventu- which something is know, all probably you as ation, radi- atomic So right. years, thirty or twenty next the within cancer, of died set film that on worked who person single every know, you but happens, just it radiation,' atomic of cloud big a look, 'Oh go, suddenly don't you radiation, atomic see don't you know, didn't they and working, were people these where to arr, across, blown was and bombs the off came it ation, radi- atomic of load whole a but time the at know didn't they and direction, this in blowing was wind the day that happened just it and bombs, atomic testing were they were, they away miles five about and here, valley a in forth, so and on so and stars, other the all and cameramen the all with with, filming — of kind was Wayne John and, and West, Wild the know, you in, film a be would it so film, western a making were they one, the to next valley the in bombs atomic the testing were they forties, nineteen the in film the making was he when and forties, nineteen the in film a making was Wayne, John story. David: long a it's down, settle story, long a is This Wayne. John Yeah? Yeah. Students: David: Wayne? John called star film the know all you Do

space. of plenty lesson, whole the of narrative the of subplot a only really is which story his gives he reasons, these For biology. of and life of view wider much a to linked is digestion about fact small A cancer. and damage radiation as such concern, of matters other to fact this connects it And protein'. digests stomach 'the fact the —

CLASSROOM THE IN SCIENCE EXPLAINING

122

'STYLES' OF EXPLAINING

123

cells, if I damage a stomach I get new stomach cells. But in a cancer, one cell divides, it just goes mad, it doesn't make the right cells, it just makes more, and more, and more cells, and you get a lump, or a cyst. Now one way to live, to — to — to deal with a cancer — if it's small enough, early enough, is to cut it

out and throw it away. Later on, you can try and attack the bad cells, with, with chemicals, called drugs, or [I with atomic radiation [] but stomach cancers, because the stomach's got no nerves in it, you don't really notice you've got stomach cancer until sometimes it's too late, to do anything about it.

It is clear that explaining through story-telling follows no simple linear form. Here, within the 'story of digestion', another story is embedded (John Wayne), within which there are further stories (a radiation accident). Also, different modes of explaining may co-exist. So far, in our example, part of the explaining can be done in a straightforward factual way (cancers are the result of uncontrolled replication) and partly through the telling of stories.

The resolution of the story again relies on the conceptual 'backbone' (digestive system as a tube) and recruits everyday knowledge ('connect it up to the rest of the tubing'): David:

What they did with John Wayne, was to cut his whole stomach out. And he lived for another ten years after that, he died when

he was kind of eighty or something like that, he, you know, he was an old man when he died, but he'd had his stomach, his whole stomach removed, and they took just that bit of the tubing there Student: But — David: connected

it up to the rest of the tubing, and [] the job of the stomach is to digest, mainly is to digest protein, and the rest of the system could manage without the stomach. John was vegetarian when, you know, really a vegetarian, yeah, so, so basically, he survived.

The overall message carried by the story (stomachs digest proteins) is preserved despite the detours into other matters. Stories have a robust structure and yet are flexible enough to accommodate additions or omissions. Later in the same lesson, David tells another story. It is the story of the fur-trapper who accidentally shot a hole in his stomach, a part of which we used in Chapter 2 when thinking about creating difference. Here we reproduce it in full, because we are interested, precisely, in showing the whole 'performance'. So, it is the story of an accident, followed by a surprisingly unexpected course of events which led to an increase in scientific knowledge. As a teaching device, it is not only an example of producing difference through surprise, but also one of 'insinuating knowledge' on the back of a truly gripping if macabre story. Contained in it are messages about the origin and nature of scientific knowledge, as well as knowledge about how the stomach functions.

he then and ho-ho,' you, haven't have, you yes, oh awa—, get 'Oh said, doctor the and myself,' through hole big a shot have I doctor, 'Look said, and fort, the in doctor the to the, to uh, went, he and fort, the to back went he yes, story true a is This

true? this Is

David: Student:

credible? even yarn this is factor: that on focus students the all of first that ways, many so in however, vast so is here produced difference The constructed. be to meanings new in result will which information new integrate to difference necessary the creating and body human the about understanding and knowledge current their with students confronting is He surprise. of element an producing merely not is teacher the developments, counterintuitive providing by However, memorable. story the makes and attention catches events of sequence unexpected The fort. the to back went he and up, himself wrapped he conscious, was he and up, himself wrapped he Anyway, here. through way the all hole big a — a left and well, as away back his of bit a took back, the out went bullet the and stomach, his through hole, big great a blew stomach, David: the through here, right himself shoot to managed he and [Laughter]

himself, shot he beaver a shooting of instead and gun, his with out went he day one because trapper, useless a of bit a been have must Martin St. Alexis Now Martin. St. Alexis called Frenchman a was trappers the of one and ago, years hundred two Canada in trade, fur massive a had They right. furs, the selling and them, skinning animals, trapping by money its all make to used Canada — ago years hundred two make, to used — to used Canada place, big really really a is Canada — trapper a was there was, happened what see You right. Canada, in fort a in worked who Beaumont, Doctor called doctor a was stomach, the inside happening was what about lot a such ever discovered who blokes these of one and stomach], own his [pats things these arr, these, in on going was what ing discover- all of first were people when ago years hundred two maybe on going was research this know, you meat. over out it wringing stomach, the of contents the the, taking by that found he and out, it wringing and sponge the collecting was he and so, sponge, of bits himself feeding was who I?, didn't man, Italian the about week, last you told I right. stomach, the inside happens what learnt people how is this people, how is this this, to listen okay, Right, one. good a that's Oh, .

Students:

.

No.

yet? Martin St. Alexis about you told

haven't Ohhh,

I

No.

Mmm. I?

haven't trapper the about story the you told I've

David: Students: David: 2: Student Student David: 1:

CLASSROOM THE IN SCIENCE EXPLAINING

124

'STYLES' OF EXPLAINING

125

said, err, he must have said to his assistant, 'This bloke ain't gonna survive, look how much, he's blown half his gut away here.' So he — he put him to bed, and he wrapped him up, and he left him to die, and the next morning he came back and Alexis St. Martin was still alive. So he must have changed the bandages and looked through this big hole, and thought, 'Oh blimey,' you know, 'What next?.' Anyway, he left this bloke without trying to stitch him up, 'cause he thought, well, the bloke was going to die. Then he realised the bloke was actually going to live, so, after a couple of days, the doctor started to try and stitch him up, but he'd left it so long, that the hole, where the bloke'd blown through the skin, and through the stomach here, the hole, had — had, started to heal, it hadn't healed properly, and, and the skin had stuck to the hole in the in the stomach, so he tried to stitch it up, but as much as he tried he couldn't, he left a hole there. So he — he bandaged it up, and after about a week or so the bloke was still alive, and he had this big hole that poked through into his stomach, so the doctor, must have said to him, 'I'm sorry about this, you know, I didn't expect you to live, a bit unfortunate, you've got this big hole there, haven't y—, but you'll be alright won't you, you can just walk around with a big bandage stuck on here, —

and just, you know, don't lean forward when you eat your breakfast, 'cause it'll all fall out, you'll be alright.' And then suddenly the doctor thought, 'Wait a minute, this means I could

look through that hole, and see what's happening to the food while it's being digested.' Student: Oh, and he could see.

What follows next is an explanation of a systematic, controlled (though unorthodox) 'scientific' procedure, given through an account which is clearly meant to fit in with similar descriptions or personal experiences of students when carrying out tests in science.

David: That's right, so he said to this bloke, he said, 'Look, why don't why don't you just stay here for a few days, and — you know — just have free breakfasts now and again, and I'll just have a look thr— look through this hole, and see what happened to your breakfast as you're eating it?' So they did this, and the doctor wrote these great long diaries of what was happening, he took bits of — he took bits of boiled egg, for example, and tied the bit of boiled egg onto a bit of string, stuck it through the hole, and then he st— took the time, 'Eight o'clock', 'ni-', you know, 'nine o'clock', stuck a boiled egg through, [mimes waitingj 'five past nine', pulled it out, had a look, to see what was happening, wrote down what was happening, stuck it back in. And he did this for day after day after day, with all sorts of different foods, sticking —

meaning. with fact material invest they picture; theoretical a serve events material make They 5. Chapter in them discussed we as demonstration, of functions the essentially have surprisingly, perhaps this, like narratives that account above the from clear also is It narratives. into worked functions and parts these just of account dynamic a with tem sys- digestive the of functions and parts of list a been have might what replaces thing whole The way. integrated an in emerges system digestive the of processes and entities of understanding the which in lesson a creates structure explanation whole The cancers. about example for explanations, extra find we them alongside and Within it. about know we how and does system digestive the of part what explain then stories The hole). this through goes it as food to happens (what terms simplified in problem the framing with starts lesson The explanation. of structures juxtaposed of and nested of example another have we Here scales. different at existing explanation about before, made have we point general a illustrates entirety its in story The digestion. of process the and components its system, ive digest- the about story main the to back attention call remarks last teacher's The out. dropping from knowledge of set this stop to bandage sufficient is story This fashion. riveting truly a in and introduced, been have structures and elements relevant of number large very A not. believe we though ing, teach- of way uneconomical an seem may story this form, this in Displayed

duodenum. the called is which intestine, small the of bit little first the into goes it and on, food liquid the squirts, and squeezes, stomach the then and liquid, to turned it's hours eight about for stomach the in been it's time the by hours, eight about for stomach the in stays stomach, the into gullet, the through down goes up, chewed gets food said I've far, so — said I what've so — got you've When stomach. the inside happening was what discovered they how that's Anyway, David: mode. information-giving direct a to returning and story, the of peculiarities the from away and hand in topic biological the to back focus the bringing said, been has what of summary the signals and mode telling story the from transition the with helps end the at touch humorous The out. dropping breakfast his stop to bandage his with that, after presumably, lived, bloke The so. or months six about know, don't I for, this did they so experiments,' more some do and come to money more you pay I'll on, come look, no, 'Oh said, and cities, main the of one in know, you down, went and him, after chased he that subject, his lost having err, his lost having about worried so was Beaumont Doctor er, and away, ran he and it with up fed got Martin St. Alexis that was happened what eventually — was this And on. going was what see to looking out, it pulling hole, the through it CLASSROOM THE IN SCIENCE EXPLAINING

126

OF EXPLAINING

127

'Say it my way' Another style of explaining is to focus on 'the right way to talk about things'. We have chosen an example concerning the right way to talk about sound waves — an example already discussed in Chapter 4, as an instance of 'didactic transposition'. It comes from a Year 8 class in an all-girls school. The teacher (Alan) has shown the students different sounds associated with different images on the screen of a cathode-ray oscilloscope. Now, at this stage something new happens: the transformation of sound into a new entity. A space for new meanings is opened up, when sound is transformed into something to be seen, not heard. Alan's efforts concentrate on making the students talk about what they hear in terms of what they see. Alan:

Now then, the cathode-ray oscilloscope can't display them like that, so how does it try to display the different types of sound. Yes?

Student: . . by making different lines and different shapes. Alan: Okay different lines different shapes. You should see if we get .

a nice pure note you should see a nice s— smooth wave like that [gesture of sinusoidal wavel going across the screen.

A further level of complexity is to be added, however. Changes in what is heard become changes in what is seen, but these are also to be described in a new language. The next stage involves paying attention to selected aspects of the images seen on the screen and describing what you see in a particular way. Changes like those in the pitch of the sound and in the corresponding shape of the trace on the screen, are given linguistic forms which link them.

Now then, if the sound gets louder, what happens to the trace that we see on the screen? Yes? Student: It gets higher. Alan:

Alan:

Okay. The trace gets higher. Okay? Now then, technically speak-

ing using the correct words, what happens to the amplitude of the sound? Yes? Student: It increases. Alan: It increases. Brilliant. Alan:

If the sound became quieter what would happen to the ampli-

tude? Yes? Student: It would decrease. Alan: It would decrease. Good.

The language is one in which what is seen is not sound, but 'the trace', but

in which the sound makes the trace. So the trace is described in simple observational terms ('It gets higher'). Then this is translated into another more theoretical language, to do with 'amplitude'. The trace getting higher is not merely a trace getting higher; it has meaning — that an amplitude has increased. Next a linguistic form to link sound directly to amplitude is worked on. The language being developed here derives from a culture which

decreasing? or increasing it Is length? wave the to happening actually is what so together, closer squashed, get to going are waves the that said already we've higher get to going is sound the If lines. wavy the on points corresponding two any or troughs two or peaks two between distance the — wavelength The wavelength. [Inaudible]

Alan: Student:

Yes. is? name that what a had trough a and

remember anyone Can name. certain

trough a between or peak a and peak a between distance the that said You OK? wave. a out drew You way. different a in it put me let — actually we can What waves? those on make we can measurement what then, Now out. spread get They wider. get They

Alan: Student:

happens? Alan: what lower, voice] pitch low a in [speaking goes sound the As definition-statement. a alds her- signal explicit the Here way'). different a in it put me ('let change a signals explicitly he sometimes but out'), spread get 'they wider', get ('they said is something how changes just Alan Sometimes points'). responding cor- two any between 'distance. to peak' a and peak a between 'distance (from complexity or elaboration greater of direction the in sometimes tried, is another way, one something said having ground; linguistic the shifts continually He ways. various in them use to students getting and them using by terms for meanings up building into work of lot a puts Alan sound. about talking of way new the of part as introduced being terms new the of explanation the in part crucial a play rewording and Rephrasing .

.

—

—

Rephrasing experience. auditory everyday an for constructed been has meaning visual—abstract A screen. the on see students his which trace' the of 'height the of meaning the way dramatic quite a in modifying is Alan changes, ex- of sequence same the in term either using by However, understanding. students' the for changed has little very that seem may it surface, the On — frequency OK? frequency the is changing is that all Alan: changing is that All changing. not is loudness the No,

the

is

No. Student: Alan: [] there? changing amplitude the Is other: the of terms in one about sentence a rephrases it, about remark any making without Alan, Thus alternatives. as them treating to shifts it connected, are two the that directly saying language the of Instead interchangeably. them using starts simply Alan time, a after But lesson. the in point this at times several rehearsed and practised are amplitude, and loudness between that including links, Such .'. sounds.. amplitude 'Large like, things says routinely CLASSROOM THE IN SCIENCE EXPLAINING

128

STYLES' OF EXPLAINING

129

Student 1: They're increasing. Student 2: [Inaudiblel decreasing. Alan: The distance between two peaks? Student 1: Decreasing. Alan: OK. Good. I thought you knew the answer to that. So the wavelength is decreasing as the frequency or pitch is increasing.

Typically of the style 'Say it my way', after a period of such successive rephrasings, Alan moves to crystallize them into an 'official' version which is dictated to the whole class or written on the blackboard to be recorded in the students' books. Alan: We basically were wanting to finish with a few sentences that will say [starts speaking with a slow impressive tonel when a sound becomes louder, the amplitude increases; when the sound become quieter, the amplitude decreases; the sound becomes higher, the wavelength decreases; the sound becomes lower, the wavelength increases. [Speech returns to normal I OK. Has anybody got all of those down?

Is this just a word-game? In 'Say it my way' the task necessarily involves explaining new terms. But it cannot be merely a word-game using new words to label new ideas; no such game could work. Work has to be done grounding new terms, often in action or in metaphor. In the present case, the new terms can be grounded in the visual representation of sounds on the screen, and their associated metaphors (see Chapter 4). Work has also always to be done relating new

terms one to another. Indeed this is the essential part of the work to be done, because a specific 'way of talking' is such just by virtue of making ideas hang together in certain specific ways. The sentence, 'The amplitude has a

high pitch' makes no sense because its ideas are disconnected. Its English grammar is fine; its 'scientific grammar' is hopeless. Learning the 'scientific grammar' is learning to 'Say it my way'. In this final extract we seem to see Alan going through a rather mechanical exercise in sentence construction (text in SMALL CAPITALS corresponds to

the word written on the board as well as spoken): Alan:

[Speaking aloud, making long pauses, as he writes on the whiteboard] As A SOUND [] BECOMES LOUDER, []THE AMPLITUDE

remind me

what the amplitude does? [I Student: Gets higher. Alan:

Higher or how could we? — what word would fit into that sentence? [I

Student: Increases. It increases, good. So the amplitude [] INCREASES, good. Number

Alan:

2 []AS A SOUND BECOMES [I QUIETER [] sh shhhh [I THE AMPLITUDE

[I What does the amplitude do? The word that will fit into that sentence. DECREASES.

move: to continents the for call to seems explanation whose fact curious a with begins He way. different a in things see to students his get to has he So feet. one's under moving and active as but home permanent stable a as not Earth, the of view unsettling and new whole a reaching on depends It all. at easy not is explain to has he what Actually, schooling. to relation in utility 2: Chapter in considered we which difference creating of forms cruder and simpler the of one uses David Here

straightforward. so it's because business in you're then exam, the in questions are there if this. understand you if hand, other the on ten, level for simple too it's because ten, level on on, this put to error an committed has government the know, you like, of, kind it's and simple, dead it's think I said, I as today, this understand and try to you want I simple. quite really is which something there's that you to said I've David: .

.

.

.

.

.

.

promise:

a

with

starts David tectonics. plate about is 10) Year (in lesson This styles. personal particular not and explaining doing of ways are here describing are we what that point the make to helps which - David by lesson another on focus we it, illustrate To way'. my it 'See called have we which this is It world. the of vision special a enforce to somehow need explaining of kinds Some

way' my it 'See that. exactly than more no as it see will way' my it 'Say style the to subjected students that danger real a is there So experienced. are they before seen be cannot advantages The it. has one before thinking, of so and talking, of way new a having envisage to difficult very is it because them, tell easily cannot He headed. is way' his it 'saying where of vision this to party be, cannot and not, are students Alan's pay. to price a is there But lesson. of kind this motivates end the in which right', it 'say to students getting just than rather this, is It formalization. abstract of one to perception immediate of world a from transformation, massive a though part-way are hears' one sounds 'The graphs. and equations with starting systems, formal further yet in represented be will relationships whose and waves, describe values whose variables into transformed be to destined are etc. 'wavelength', 'frequency', 'amplitude', terms The aware. well be will students the yet not if — Alan which of power, latent much has knowledge new This saying. of way new a as well as seeing of way new a for — kind new a of word new a for but word, suitable a for merely not asks sentence?' that into fit would word 'What question, The 'increasing'). is ('amplitude' doing is entity abstract an what describing verbs become ('louder') perceptions describing adjectives Correspondingly, increases'). ('amplitude concepts to louder') becomes ('sound percepts relate They job. important an do sentences These —

CLASSROOM THE IN SCIENCE EXPLAINING

130

'STYLES' OF EXPLAINING

131

David: And I think people began to realise, during the course of this century, that when they looked at the map of the Earth, it looked pretty obviously, as if, kind of, bits fitted together. a rather unusual one in which mountains and valleys under the sea are as prominent as those on land. It is not even too easy to see the familiar forms of continents, and David spends time pointing them out. Why is he doing this? In the style 'See it my way' there is generally an explanation waiting to be given, which is what decides what phenomena are counted as interesting. And David has such an explanation — the moving of continental plates over the Earth's surface. Thus in the next extract he concentrates on one phenomenon for which that explanation will be able to account.

David shows them a map —

David: So the map is quite complex. .

. First

let's look at the spots of

land in the middles of all this mess. Here's America in the middle [teacher shapes out the Americas with his finger]. [] Over here is Britain, a bit of Europe here, a bit of Africa down there. Now, all the different colours [ ] on the Earth's surface, are what kind of rocks are being formed where. [1 But what I just wanted to show

you, huh, it's very difficult to show you, is this bit down here, where this bit sticks out here [the teacher shapes out a bit of South America], can you see this bit of South America sticks, sticks out

here, and just here, look, there's this sort of bit of Africa that's got this kind of armpit, and if you look at these two, you can think to yourself, well look, that bit fits in there, that's convenient, isn't it, how come there's just, you know, a thousand miles of ocean in the middle, but that bit looks like it fits in there?

Here then we illustrate again a point made first in Chapter 1, that what gets explained depends on what explanations are ready and waiting. If in science itself, phenomena can be envisaged as in need of explanation, in teaching science it is almost the other way round. The existence of explanations decides what questions get asked. The existence of an answer is the reason for posing the question. David makes the question more real by describing

how the ideas evolved, starting with the now discredited idea that mountains formed by the folding of the crust of a cooling and shrinking Earth. David: Now, through the course of the nineteen twenties people thought

what was going on, was, as the planet is cooling down, it was forming a skin on the surface, and as it cooled down more, and it cooled down more, and it cooled down more, it started to shrink [holds his hands in a ball and 'shrinks' it] and as it started to shrink, the skin on the surface, started to form itself up into, into, into folds, and bends, and contours, and that's the way, they believed, in which the mountains were formed. They were cooling down and then crinkling up and forming this, this cold crinkled lump, OK? Basically, through the nineteen twenties people began to

5. Chapter in demonstration 'failed' his described We doesn't. it and — works it if care much doesn't he that but Earth, the of interior the in convection illustrate to show to demonstration a has he that fact the by shown is imagination the to basically is appeal David's That volcanoes. making and rising rock molten represent to hand upper the of fingers through up hand lower the of fingers pushing then and other the below hand one sliding by another under dives plate one when happens what symbolizes David vivid. more even are gestures the Later

ironically]. [said movements' conservative 'little these of one by destroyed was Francisco San of whole the 1906 in again] hands [moves earthquakes cause other each, against move just plates the when plates, these of movements little So world. the over all earthquakes cause which things are shifting, occasionally just and again] edge to edge hands [puts that like — against plates of pair A all. at conservative too was it think wouldn't you plates these of one on lived you if Although term]. technical a — solemnly and slowly [said margins' 'conservative called are These other]. the beside along hand one [slides this like shift they again, and now every and, edge] to edge hands two [puts together sitting are which plates the is One ways. possible different three in move They'll hands] the [moves moving are rock of plates those and handi other the out [holds here plate a and hand] one out [holds here rock of plate cool a there's So plates. individual of series a formed They lump. single one formed haven't they but yes?, cooled, has — has planet the of surface the on formed that's rock of skin the of — of lumps these down cooled planet the As this. is on going is What around. moving Earth the of chunks great about talking are we because it, understand to difficult quite is it that massive so It's massive. very is hand, other the on but simple, pretty is on going is what And on. going is what realize to begun have people years twenty to ten last of sort the of course the over gradually And David:

continents. of movements possible the mimic to hands his using gesture, of lot a use to is does he What real. it make to can he resource every use and imagination, to appeal must He argument. logical to or demonstration, to fact, observed to appeal cannot He drift. and move plates enormous which in way, new another yet in Earth the see to them get to needs now David them. about questions new and phenomena new to pointing explained, be to world the change may above, suggested we as theory, this And theory. a of terms in

rationalized are facts way', my it 'See In custard. on skin wrinkled as Alps the see to easy not is it be: to needs it And active. and concrete vivid, very is language The way. one in Earth the see to them get to tried has David forth. so and on so and oceans have you come how and continents have you come how explain really not did it because satisfactory very wasn't really this realise CLASSROOM THE IN SCIENCE EXPLAINING

132

'STYLES' OF EXPLAINING

133

This is, perhaps, a rather special case of the style 'See it my way'. At least what has to be seen in a special new way — the Earth — is and remains a concrete object. Seeing in a new way becomes even more important in other areas of science in which entities have their basic nature altered. Obvious examples include matter being made mostly of empty space, or diseases being caused not by circumstances but by germs. When it comes — in much later learning — to gravity being just curved space, the need to see things in someone else's way becomes the heart and whole of the problem.

teachers what time the of some If described. be to needs each of contribution the and things, these of all do do they But events. material to meaning new a gives which account an reaching finally purpose, the for transformed ledge know- scientific using job, the do to entities the construct then explanation, an for need a establish first sequence simple some in not do teachers So 7. Chapter in suggested we as time, the all together happen all they trary, con- the On other'. the after 'one happen these that suppose not do we ful, meaning- matter making and knowledge, transforming entities, constructing difference, up opening of tasks, main four the identify we therefore, When, working. tions explana- of account our of parts component the see we how is This once. at dimensions several on described be to has explanation any that is sequence con- The polyphony. of kind a in time, same the at all happen things other and These done. be to communication the of organizing and structuring some and others, to respect with taken be to position some say, to something least) (at is there communicates, one whenever generally, Quite works. tion communica- how just is That once. at on going necessarily are things many that is communication) of kind any matter that for (or classroom science the in explanations describe to trying in faced be to problem fundamental A next. come to need might what to forward looking and make, to wish we claims what explaining tions, assump- underlying our summarizing done, have we thihk we what describing together, book the of threads the draw to try will we chapter, final this In

forward looking and Concluding

NEXT? WHAT AND NOW, WHAT 8

Chapter

WHAT NOW, AND WHAT NEXT?

135

do looks more like one of these dimensions than like the others, the others are always there in the background. It was for this reason that, when introducing these ideas in Chapter 1, we could draw so heavily on a very few examples. If that seemed forced at a first reading, it may be useful to reconsider the issue now. We could, for example, treat the case of explaining the gut of an earthworm as opening up a different way of seeing things, as work towards constructing the entity 'digestive system', and as transforming a biological structure into a piece of topology, using devices such as analogy. All were there to be seen, in a few minutes of speech and a diagram, and all working together as opposed to being strung in a chain. In broad terms, then, what we believe we have done is to identify — from a particular semiotic point of view — some main aspects of what must be

involved in any act of explaining science in the classroom, and then to illustrate in considerable detail how these very general aspects can be seen and described in particular cases and how they can then be used to compare and contrast cases. Further, in Chapters 6 and 7, we have sought to show how in different contexts, with different people, explaining different things, the dynamics of the situation issue in a variety of ways of doing the job of explaining — different strategies or styles. Despite their differences, however, each style still has an account at the same general level — the level of what any kind of explaining has to do.

Assumptions In all this work, we have started from a number of broad assumptions about

the nature of communication and of scientific explanations. These were outlined in Chapter 1, but it may be helpful to summarize them again here. We take communication to be continuously active, transformative or constructive. We do not accept a view of communication as using fixed terms to refer to fixed realities. For us, each meaning made is in some measure a new meaning, not an old one reshuffled in a repetitious game of saying the same things over again. Those with something to say are necessarily always saying something new, sometimes radically, often only slightly. Those with something to understand have necessarily to make that understanding anew for themselves, again only sometimes radically but always to some extent. It is from this that communication gets its dynamism and the source of its continuous transformation and change. We also take communication to be integrated and multimodal. In the past and still in many respects today, our Western culture takes language to be the dominant mode of communication, and within that gives pride of place to writing over speaking. Other modes of communication, especially graphic and pictorial modes, are generally thought of as adjuncts to the 'real thing' as members of a supporting cast. Much evidence, from the dominance of television to the widespread use of images in advertising and in signs, points in the opposite direction. At least, we believe, full attention has to be paid —

examples real of number large a to applied classroom, science the in explanations describing for language a • kinds: two of therefore are results Our knowledge. scientific and knowledge students' between distance conceptual the and reality, material to ideas and talk of relation the both notably science, of characteristics special the of because with, deal to communication of theories current for case ficult dif- a as important also is problem The anecdote. and intuition experience, from wholly work to have teachers science advise or train who Those room. class- the in science explain to is it what of account principled no exists there science, in learning to and classroom, the in language to past the in paid attention research much despite because, important is problem The achieved. fact in have we believe we what is This teachers. science by usable and to intelligible be also should It basis. theoretical coherent and clear a have to and data empirical good on based firmly be to needed language that And explanations. such describe to guage lan- a develop to us required This classrooms. science in teachers by given explanations describing of way a find to was ourselves set we problem The

Results enriched. further became themselves they process the in that and fruitful, and productive us, for least at proved, they that — more say can we Perhaps strain. the under crack not did they work, present the of course the in that say can we least at But prejudices. our doubt no and understandings, theoretical initial our lize crystal- They out'. 'found we things course, of not, are assumptions These them. to done be can what and do can things what on — actions on end the in rest must it then words to pointing words of circle the escape to is meaning If meaning. constitutes what about assumptions our with consistent also is entities of notion our But 'entities'. of notion our draw we that conception this from part in is It

explained.

be to phenomenon the produce to together acted have can entities these of some how tells explanation An them. to done have and do can they what on and reality of constituents the be to taken are what on views; world entific sci- on rest explanations scientific that is view our words, few a in marized Sum- seriously. take to difficult is view this physics, of parts theoretical more the Outside laws. scientific from deductions like as seen best were they that was explanations scientific of view general the recently, Until book. the out through- repeatedly used and 1 Chapter in out set position a explanation; scientific of nature the about assumptions of set a from start also We role. significant and special a performing each together, integrated modes, such several involves communication that is assumption Our actions. and gesture communication of modes other these in include we And language. with par a on them to CLASSROOM THE IN SCIENCE EXPLAINING

136

WHAT NOW, AND WHAT NEXT?

137

• issues and problems for theories of communication more generally which arise out of the distinctive character of science and science classrooms

We will comment on each of these in what follows.

Describing explanations in science We repeat below from Chapter 1 the main components of our language for describing explanations, and then discuss each briefly:

• scientific explanations understood as analogous to 'stories' • an account of meaning-making in explanation, itself with four parts: creating differences constructing entities transforming knowledge putting meaning into matter • variation and styles of explanation We see in scientific explanations an underlying structure analogous to that of a 'story'. There is a world of protagonists (electrons, genes, etc.) which have

their proper powers of action. They enact a sequence of events (a current flows, proteins are made). This sequence has an outcome, namely the phenomenon to be explained (a lamp glows, a cell develops). The point of the analogy is that none of these three components can, in science, be taken for granted. Much explanation has to concern the protagonists and the events they enact. Nor may the phenomenon to be explained be at all obvious (e.g. motion of the continents). For these reasons, we need an account of how teachers create a need for explanation — in communication terms, a difference to be bridged or resolved.

Ways of doing so include promises of clarification, eliciting differences of opinion, using stories to suggest ideas, showing counterintuitive results and creating expectations. Unlike everyday stories, scientific explanations have protagonists unknown to students. Electron, genes and other scientific entities have therefore to be 'talked into existence' for students. This requires explaining what they can do, have done to them and what they are made of. And they will persist, turning up again and again in new and often unexpected contexts, as real things tend to do. School science is necessarily a carefully versioned form of scientific knowledge, transformed rather than merely 'simplified'. One of our examples analyses the way sound is transformed to become visible in an oscilloscope. Essential to such transformations are analogy and metaphor: the eye as a camera; atomic orbitals as spaces to fill up. Demonstrations are essential to scientific explanation. Whilst they are usually thought of as 'showing how things are', we show instead that their main function is to invest physical events with special kinds of meaning. They press matter into the service of theory. Explanations are of many kinds, done in many ways. The features which

explana- 'an to corresponds that unit formal fixed no found we contrast, By

explanation'.

of 'genres of speak indeed does schools secondary of genres textual on work Some terms. clear relatively in described be can example, for report, scientific a of form the genre: of concept the through sense common this reinforced has form, textual on work related and discourse, scientific on work recent Some you'. thank 'no, or please' 'yes, is offer an to response a form; rogative inter- an has question a meaning: and form between correspondences clear relatively are there that been generally has linguistics of sense common The forms of meanings and explanation of Forms

interest. special of be to proves which done, being is what adjust to continually has teacher/communicator the way the and situation, this of structure clear relatively the is it theory communication of view of point the From together. this all bring to is it task whose teacher the and science; into inducted be to is who student, the curricula; into knowledge this turn which 'education' of institution social the knowledge; of kinds various its with science, of line discip- the these: least at are difference of determinants situational The curriculum. that of aims the achieving for timetable set a with curriculum, clear a is there as form, sharp in appears issue this particular, in education science in and education, In there. visible less much but interactions, everyday of phenomenon a also is 'Difference' interesting. science make to parlance, ordinary in them: to relevant all, above and them, by understood students, to known difference that make to part, large a in is, teaching of task The student. the by not but teacher, the by understood is difference this of relevance The science. of knowledge namely difference, of area ous obvi- one exists student science the and teacher science the Between field. a such into brought be can competence, practical and technical theoretical of fields to outsiders how is view of point communication a from issue The difference Creating

generally. more communication in importance of issues to pointing as it seeing view, of point wider rather explanations describing for framework our at look to now turn We a from

communication as Explaining explanation. the to appropriate language the using practising and are', things 'how of vision new a enforcing stories; in explanations encapsulating ideas; and knowledge students' using and activating explanation: of styles distinctive of number a identify We matter. subject the of nature the and evolves, work classroom the way the teacher, the of experience and resources knowledge, the tions, explana- other on dependence their include them between differences generate CLASSROOM THE IN SCIENCE EXPLAINING

138

WHAT NOW, AND WHAT NEXT?

139

tion', whether at the level of the clause; or of the sentence or of a sequence

of sentences; or in the form of a text with clearly identifiable boundaries. On the contrary, we find that explanations may stretch across whole texts, series of whole texts (as explanatory sequences), or across smaller parts of texts. We therefore see the unity of explanation not as deriving from the form

of texts or of units of texts, but from patterns of factors which influence explanatory contexts. The textual units which express or realise explanations are quite diverse. Their diversity is to be accounted for in terms of the social and institutional structures of explanatory contexts. Thus we have not arrived at a taxonomy of explanatory forms; but have instead developed a means of describing characteristics of explanatory contexts. Styles of explanation

One remarkable result is the recognition of a variety of 'styles of explanation'. These 'styles' have their origin in a number of factors. First, there are undeniable differences between teachers, which seem to be the result of personal histories and experience, the effect of the disciplinary issue dealt with, and broad pedagogical and epistemological dispositions training and traditions. All of these interact with — and may be triggered by — characteristics of the class collectively or of individuals in it. So for instance, the use of narrative, 'telling a story', can simultaneously have the multiple functions of establishing rapport, introducing a new topic, and insinuating relevant new knowledge — thus opening the essential difference which prepares for the coming explanatory sequence. Or, eliciting what seems like ordinary, common-sense knowledge from pupils and turning it successively more and more into the form of scientific knowledge, may depend on the suitability of the subject matter, on the teacher's confidence in managing the process, and on an established history of rapport between class and teacher. 'Styles,' however, are not just static, fixed dispositions of individual teachers.

In the course of a lesson, there are constant adjustment, changes, shifts, in the form of interaction. So while we can sometimes see a relative stability of style with a particular teacher, and in particular of that teacher with a given class, this stability is not in the least anything like rigidity. We expand on this in the next section. The dynamics of a multiple communicational environment

Teachers use a range of modes of communication. A sequence may, typically, involve: speech, including the spoken delivery of written language (or 'language for writing down', as in the dictation of bits of curricular knowledge); drawing on the blackboard of diagrams of various levels of complexity; prepared objects used in demonstrating; images from books; gestural forms of delivering information. It is quite clear from our video-recordings that one has to speak of a multisemiotic environment, in which language is clearly important, but not solely so or even at times predominantly so. Consequently, there is not only constant

thought usually are what together bring to us enables which generality, and power certain a it for claim do we But classroom. science the in tion explana- at looking of way only the is ours that claim course of not do We

claim? we do What process. semiotic the be to taken usually is what of reversal a theory; resent rep- to made is Reality issue. at is which reality material the of elements by 'encoded' is reality theoretical of aspect an demonstration a in contrary, the On reality. material of aspect an 'encodes' representation the that is which assumed, generally that to direction opposite the in works sign-making the Here environment. multisemiotic this of elements all of connectedness the shows itself in demonstration the of phenomenon The representation. its to world material from way, one not is processes these of directionality The remaking. constant of one is process the used: being merely or simply representation of resources stable these with systems representational stable of one from removed far is picture the Again, transformations. these cing produ- and managing of means the as used is system semiotic complex the education: science of domain the for as communication of systems the for much as consequences has This transformed. constantly are elements its of and environment explanatory the of aspects all teaching, of process the In like'). 'they give', ('they entities active into world that of enlivening an to there), out world objective the in .' are ('there position distanced objectively an via elements) and electrons, our — have' ('we proximity personal from movement a completed has she .', like. 'they .', give. they '. to .' are. 'there a to .' have. we here '. a From table. periodic the of elements the towards class a of members of perception the repositions time) class of so or minute a barely takes sequence the (though gradually teacher a when as students, or teachers either to certain, feel we invisible, ways, minute most slightest, the in pen hap- may these All knowledge. towards students of positioning the of and knowledge; of transformation of communication; of modes between shifts of tactics; of change of dynamic: constant a of one is emerges that picture The . .

.

.

.

.

.

.

.

.

processes and mechanisms conceptual and Semiotic

description. written a than effectively more or effectively as system', 'digestive entities of structure larger the in 'intestine', entity the establishes blackboard the on diagram A description. spoken a than tellingly more or as 'subduction', entity theoretical the build helps other the below hand one of teacher the by movement pushing slow The entities. of construction the in part their play each modes various the that insist to important is It time. a at one than more with harmonies playing usually are they And effects. own its with each instruments, several playing were, it as are, Teachers communication. of mode the of salience relative the in adjustments constant also are there but mode, of terms in adjustment 140

CLASSROOM THE IN SCIENCE EXPLAINING

WHAT NOW, AND WHAT NEXT?

141

of as rather disparate parts of the activity of teaching science. Our claim is that our new language of description provides a framework within which we can give accounts of many different ways of explaining; accounts which can bring out similarities and differences between them. We do not claim to have identified every possible kind of explanation. But we do claim that this framework will prove workable and valuable in looking for other ways of explaining, and we can already describe a large number of examples. The framework we offer is not one from which one can 'read off' how an explanation is going. It does not provide checklists of features. What it does provide are the basic sets of questions which need to be asked in each case, together with a collection of examples of answers on which others can build. We hope that the framework will prove to be of value in helping teachers and those engaged in their professional development to recognize and reflect on cases of explanation. Simply possessing terms with which to try to describe what one is doing is a big step forward. Naming is half-way to recognizing, and recognizing is half-way to thinking again. New perspectives in science education

We also claim to have done something new in research in science education.

For almost two decades, the main focus of research has been on students' personal understandings. It has yielded valuable and important results. But it has tended to work from an assumption (a particular reading of 'constructivism') that knowledge cannot be 'transmitted' from teacher to student, so that what has to be attended to is the student's own personal construction of knowledge. Our view, stated elsewhere in the book but worth repeating here, is that communication is action: that to teach is to act on other minds, which act in response. This makes it worth looking at teaching again, asking what teachers are doing and how they are doing it. We have sought to make teaching a topic of research. Our work is also relatively unusual in combining detailed observation and video-recording of science classrooms, together with a close attention to the subject matter being taught. Many studies have been done using checklists of kinds of interactions; typically these do not record the variety of modes

of communication, nor often do they attend much to the subject matter. Many other studies of the language of the classroom have, with exceptions, studied mainly verbal forms of interaction, excluding the many others we have found to be important. They have also been primarily interested, again with some exceptions, not in what is being taught but in the structure and form of relationships in the classroom.

What next? conclude the book with some thoughts about what might need to be done next, in research in science education and in research in communication more generally, to follow up the work described here. We

white of part a is 'Red' 'part-of'. as relations semantic basic such reconsider to need a be may there both In discussed. just kinds the of typology or lysis ana- an need too They entities. substance-like or object-like of treatment our than weaker perhaps is processes and events of treatment our Secondly, places. or spaces like are which entities from different radically are these all And action. bodied disem- a or object passive a either from meaning of package different very a like looks object physical acting autonomously an like is which entity an Thus involve. they which relations meaning of kinds different the of analysis further much have yet not do we classes, and clusters of membership their and parts their them, to done be can what do, can they what from derived meaning of packages having as terms general in 'entities' characterize can we although that is One attention. need which limits important some has it fruitful, and useful is explanation of analysis our that believe we Although

communication? of studies in next What science. in communication graphic on — progress in now — work new to us led has finding second The form. graphic in was content explanatory their of much that second, and classrooms, science in used little rather were books that first things: two found we on early very because work, present the in line that pursue not did We explanation. in role a play books from material and books ways the at looking to classroom, the in interaction personal from analysis the extending of ways for look to important be also will It purposes. main its of one served have will work the ance, perform- their from missing be may which elements recognize to and ives, alternat- consider to doing, are they what recognize to teachers help can it If training. in-service or pre-service of process the in teachers, by used and understood be can explanations of description of language our extent what to see to be would value, considerable of one but task, immediate more A explanations. their explain to then and themselves, explanations struct con- to students asking be would here pursue to direction obvious An duce. pro- to helped have may explanations different understandings of kind the of indications obtain to — will you what them call resources tasks, probes, tests, of construction the involve will question a such answering things, other Amongst whom?' for and when well, work explanations 'What tion, ques- obvious seemingly the answer to possible be it will kinds these all of results given Only explanations. effective of attributes the as see they what and explanation, an as students for counts what better understand to need We explanations. receives student the how us tell not do descriptions the still, important More intentions. their matches behaviour teachers' well how see to is inquiry of line important one so did, they what only but do, to ing intend- were teachers what us tell not do They ways. of variety a in use to put be — to need and — can descriptions these then classroom, science the in explanations describing of way effective an claim, we as have, we If —

education? science in next What CLASSROOM THE IN SCIENCE EXPLAINING

142

WHAT NOW, AND WHAT NEXT?

143

light, and the liver is part of the body, but not obviously in the same sense of 'part-of'. Our point here is that the field of science education provides an exceptionally fruitful field for the extension of, and challenges to, existing understandings of semiotic theories. In the everyday task of science education, the resources of communication used are wide and varied. The dynamics of that complex environment lead to a constant reshaping of these very same resources of communication: science shapes communication as well as the other way around. That in itself is a challenge to current understandings of communication. A further issue which emerges is the exploration and description of the part played by different modes of communication, and their effects

on the production of disciplinary knowledge. Much of the book has focused on questions of knowledge and understanding. But looked at from another point of view, what is going on in the science classroom changes — or can change — who students are. To understand science may change one's subjectivity. We have seen in the book several challenges to students' ideas of themselves — here let the objectification of digestion, in which a comfortable known social process is reconstructed as a biochemical machine, stand for the others. Finally, science is challenging to theories of meaning-making because of its crucial relation to the material, the physical, the ungainsayable brute material world. Semiotics, with its roots in linguistics, has for good reasons tended to concentrate on meaning-making in language between persons. The actions it grounds meaning in are communicative actions. But science has in addition a component of making sense of physical reality. The student certainly learns science in interaction with a teacher. But the student also constructs explanations in interaction with the physical world (and, of course, began to do this as a baby). We might label this 'material semiosis', as a placeholder for something yet to be understood. To conclude — an anecdote. Early in the research we observed a class in which a student took off his shoe, put it on a table, tied it to a spring balance, and tried using the spring balance to pull the shoe along the table. At the time we saw but did not record this event, since student and teacher did not communicate, and we assumed there would therefore be little relevance to explanation. But a theory of communication clearly needs to embrace acting so as to build an explanation for oneself. So this example points to yet more work to do.

show to practices, and structures social into everywhere, in, tied as diverse, more as autonomous, not as language show to been has work this of effort collective The Semiotic. Social as Language

book seminal Halliday's Michael in announced itself semiotics, social in and lysis, ana- discourse critical as known strand that particularly including analysis, discourse of and — eminently stand Labov William and Hymes Dell Bernstein, Basil of names the which in — socio-linguistics of forms many in work prior on depends It ication. commun- social in language revaluing of history long a on builds approach Our language. of effects simply

not are which meaning of structures produces world, material the of meanings the with grappling in Science, English. history, geography, in classrooms to world semiotic different a ways, fundamental in is, classroom science the that think We teachers. science of activities and objects practices, the of import semiotic the of enough ful respect- been not has work previous that think we and classrooms; science in icate commun- to is there all is language that think not do we respects: essential two least at in it beyond gone have we think We classroom. science the in language on work existing of use our acknowledged gratefully 1, Chapter in have, We time?' another at done been have this 'Could ask: to is enterprise intellectual an locating of way One communication of study the from perspective

A

now? sources. of bibliography annotated an provides section second A context. its in based is book the which on research the situate we appendix the of section first this In

Context

SOURCES AND CONTEXT Appendix

APPENDIX

145

language itself as just one social practice, and to point — forcefully — to the fact that other social practices are used to communicate and to make meaning.

A perspective from science education

The past two decades of work in science education have been dominated by two strong traditions: a tradition of emphasizing direct learning of science through practical activity, and the constructivist tradition emphasizing the student's personal construction of knowledge. Whatever their merits — and they have many — these two

traditions have combined to draw attention away from the teacher, except as a provider of productive 'learning situations'. Constructivists have rightly been concerned to eradicate the belief that knowledge can be piped from mind to mind. But that does not mean that there is nothing for the teacher to do; no scope for the teacher to seek to act on students' minds. Our focus is thus a shift away from these traditions, bringing attention back to how teachers explain — back in effect to a neglected aspect of rhetoric in the science classroom.

In doing so, we have taken account of many different ways of thinking about 'explanation', ranging from the philosophical to the psychological, taking in on the way explorations of the concept in cognitive science. But we have not tried to add to the number of such interpretations. Rather, we have drawn on them to construct a language for reflecting on explanation in an applied setting — the science classroom.

The work of the project The data on which the book is based come from an ESRC funded research project 'Explanation in the Science Classroom' (R000234916), undertaken between April 1994 and September 1995 at the University of London Institute of Education. We began by surveying existing data on classroom talk, examining video-tapes of secondary school science lessons, video-tapes of teacher training sessions, and audiotapes and transcripts of teachers' discussions of scientific ideas. A small scale survey of currently used secondary school science textbooks was also undertaken. We considered the relationships between diagrams, images and explanation in these books.

We first noted here a feature that remained important: that explanations exist on all scales from the whole chapter to a line of text. We used these materials to reach common agreement on what we were looking for and what approaches to use in analysing data.

Having made contact with ten secondary schools in the London area, four were selected and a pilot study was organized and carried out in July 1994 in two of them. Following this, the main study involved 12 teachers in four schools: Swakeley's School for Girls (grant-maintained all-girls comprehensive), North Westminster School (LEA mixed comprehensive), Riddlesdown High School (grant-maintained mixed comprehensive), Harris City Technology College (CTC). The decision to video-record lessons was made as a result of the pilot study: we very quickly found that the teacher's words were by no means the only mode of communication, and sometimes by no means the most important. We found that essential features such as gesture, body movement, pointing, as well as references to blackboard diagrams, computer screens, experimental apparatus, posters and other visual displays, required video rather than the originally planned audio-recording. The data derive from 52 hours of video tape, of lessons involving all the natural sciences including some earth science. Lessons were recorded from the secondary Years 7 to 10, with one or two from Year 11. The recordings concentrated mainly on

from distinguished be to this in and power, of asymmetries on founded and ideological as process educational the represent They images. and action language, of interaction the to attentive are arguments, and transcripts, Their science. school on primarily focus not do so and subjects, school of variety wide a consider They student. and teacher between occurring ledge know- common towards movement a as teaching of process the terpret in- Mercer and Edwards psychology, social of background a from Coming Methuen. London: Classroom. the in ing Understand- of Development The Knowledge: Common (1987) N. Mercer, and D. Edwards, know. we what to reducible is exists what that fallacy': epistemic 'the calls he what of identification the is contribution important One science. of philosophy the in realism of defence a here provides Bhaskar Wheatsheaf. Harvester London: Science. of Theory Realist A (1978) R. Bhaskar, action. as understood is discourse which in psychology' 'discursive of standpoint the from seen argument, and explanation everyday with is here concern The Sage.

London: Accounts. of Organisation Social The Arguing: and Explaining (1994) C. Antaki, Draper). by chapter the especially (see discourse in explanations identify to 'because') as (such markers linguistic of unreliability the of evidence and causality, expressing statements about is tion explana- that idea the to challenge a are offered insights many the Amongst intelligence. artificial and analysis discourse linguistics, psychology, social ing includ- backgrounds, disciplinary of number a on draws settings social various in explanation for account to ways different of studies of collection This Sage. London: Explanation. Everyday Analysing (1988) (ed.) C. Antaki, ideas. the up follow to wish who readers guide to and work, our to relationship its indicate to text each on notes provided have We perspectives. complementary or alternative vide pro- which or thinking, and ideas our of sources main the as regarded be may which others with together book, the in to referred works of bibliography a here provide We

Sources data. the all analysing exhaustively to not data, describe to which with categories 'good' finding to directed was effort The them. revising and reconsidering then and up these writing them, analyse to which from perspectives ing develop- transcripts, and tapes the discussing and viewing by proceeded Analysis data. as used or recorded not were conversations These lesson. the in on gone had thought they what about teachers with discussions informal had we session, a recording after Typically, interest. of something doing be to about teacher a found we when moment, the of spur the on others few a collected we occasions, planned these to addition In sciences. the across topics of range balanced a covering lessons of sample a offered they what from selected and explaining, of amount stantial sub- a involving lessons, of sequence a or lesson, a giving be to likely were they when colleagues teacher our with discussed we explanations, in interested were we Because done. be normally would they as done lessons, routine ordinary see to asked We camera!). the of presence the to reactions their (including pupils from reactions some capture to able also were but teacher, the APPENDIX

146

APPENDIX

147

non-educational communication. They provide a forceful discussion of the specific features of classroom interaction, the relationship of those features to social relations, and their sometimes harmful impact on learning. Their position leans more to Vygotsky than to Piaget. Halliday, M.A.K. (1978) Language as Social Semiotic. London: Edward Arnold.

This seminal work is now old, but not at all outdated. Although challenging to linguists it is not technical in nature and is accessible to the non-linguist reader. It in several places has an explicit focus on education, but its main merit is its wide but deeply thought-through perspective on language as one aspect of what it is to be a social being. Halliday, M.A.K. (1985) An Introduction to Functional Grammar. London: Edward Arnold.

Our work in this project has been fundamentally shaped by systemic functional linguistics, which is a functionally oriented linguistics linking grammatical forms to social situations. That theory has provided much of the backdrop to our analysis. The book is fundamentally a handbook of linguistic analysis, and not readily accessible to non-linguists. It offers a com-

prehensive account of language, with many essential insights into the multiple tasks which language performs simultaneously. Halliday, M.A.K. and Martin, JR. (1993) Writing Science. London: Falmer Press. Writing Science is a collection of articles on science texts from a systemic functional linguistics perspective. The focus is on language in written texts. The

analyses identify features of the language of science proper and of science textbooks, and characterize some significant text-types (genres) of science, providing considerable insights into the language of science, the language of science classrooms, and how language works generally. A number of the articles contrast science language with the language of other subject areas. Harré, R. (1985) Varieties of Realism. Oxford: Blackwell. Harré promotes a view of the scientific enterprise as a cluster of material and

cognitive practices whose participants are bound by moral commitments. Important contributions of the book include the account of analogical explanations in science, the idea of 'policy realism', and the analysis of the different roles played by entities in explanations according to their degree of accessibility to experience. Hempel, C.G. (1965) Aspects of Scientific Explanation. London: The Free Press. We include this text as representative of philosophical accounts of explanation. Hempel develops the logical positivist philosophy of science to gener-

ate a 'logic of scientific explanation'. An explanation is seen as a deduction of phenomena from axioms which include at least one general law. Such accounts mainly aim to formulate logically necessary and sufficient conditions for something to be an explanation. See also Lipton (1991). Hodge, R. and Kress, G. (1988) Language as (2nd edn). London: Routledge. The book, first published in 1979, attempts to relate the grammar of English to the social, economical and cultural organizations of society at a particular time. It is set within the functional theory of language of Michael Halliday, but uses linguistic concepts from other theories, notably the concept of transformation. It provides detailed analyses of a variety of texts. Hodge, R. and Kress, G. (1989) Social Semiotics. Cambridge: Polity Press.

This book extends functional theories of language and communication to a wide range of modes and media of communication: images, sculpture, family structures and narratives, language, spatial organizations, fashion, comics, films, advertisement, and so on. It provides detailed descriptions of the organization, effects, and social uses of these forms.

founded science, in realism of defence stout a offers paper review long This 3—38. pp. 25, Vol. Education, Science in Studies reality'. 'Recovering (1995) J. Ogborn, analyses. our informed have which of ults res- world, physical the about reasoning common-sense of dimensions basic the of studies empirical addition in includes work The here. found be to is book our in used explanation about theorizing the of account extended An London. of University thesis, PhD Knowledge. Common-sense and Scientific of Nature the of Investigations Empirical and Theoretical (1994) J. Ogborn, framework. linguistics systemic a within situations, social and features language between tionships rela- specific the of discussion detailed and careful a with along discourse, of passages extended of analysis the for techniques of set a presents Text English Benjamin. Amsterdam: Structure. and System Text: English (1992) JR. Martin, further. read to wanting those for bibliography date to up but select a provides and explanation, and inference scientific of accounts ical philosoph- main the of descriptions offers text wide-ranging but short This Routledge. London: Explanation. Best the to Inference (1991) P. Lipton, authority. of relations social within located is learning science and theory, social by informed is Science Talking thinking. of way student's the of transformation a as than rather teacher, the by produced as talking' of way 'science the to approximating student the as construed largely is learning of process The talk. classroom from extracted be may content science how show analyses The patterns'. 'thematic calls he which science, school-subject the of tions rela- semantic the of discussion strong particularly a with transcript, analysed carefully of passages long on based orientation, linguistic a have analyses The classroom. science secondary the into research on based is Science Talking Ablex. Jersey: New Norwood, Values. and Learning Language, Science: Talking (1990) J.L. Lemke, rejects. he which views sical clas- of analysis critical a with up taken is book the of Much metaphor. on founded as language of view Lakoff's defends and elaborates book long This Press.

University Chicago Chicago: Things. Dangerous and Fire Women, (1987) G. Lakoff, book. the throughout examples of wealth a by illustrated are experience, bodily in grounding their as well as communication, and nition cog- both in character pervasive Their world. the of understanding and tion conceptualiza- our of roots the at lie metaphors that argue Johnson and Lakoff Press.

Chicago of University Chicago: By. Live We Metaphors (1980) M. Johnson, and G. Lakoff, development. for potential with but limited, is images science to attention the so and broad, is book the of scope The change. technological and social cultural, to images of relationship the and characteristics, communicational their considers also images of classification and description The interact. and other each complement may images and language how of understanding an offers It images. of analysis oriented semantically a provides Images Reading Routledge. London: Design. Visual of Grammar A Images: Reading (1996) T. Leeuwen, van and G. Kress, experience. bodily and actions human in them grounds which rationality of and meaning of theory a construct to attempt ambitious An Press. Chicago of University Chicago: Reason. and Imagination Meaning, of Basis Bodily The Mind: the in Body The (1987) M. Johnson, APPENDIX

148

APPENDIX

149

on the notion of a scientific ontology of entities, which participate in explanation. It attacks those who draw anti-realist conclusions from recent work in the sociology of scientific knowledge. Ortony, A. (1979) Mefaplzor and Thoughf. Cambridge: Cambridge University Press.

This old, but recently reprinted collection is still useful. It offers a variety of perspectives on metaphor from philosophical, linguistic and other points of view. Piaget, J. and Garcia, R. (1987) Vers une Logique des Significations. Geneva: Murionde. (Translated 1991, Toward a Logic of Meaning. New Jersey: Lawrence Erlbaum.)

Together with Piaget's earlier work, which develops the idea that thoughts have origin in internalized actions and reality is constructed, not given, this posthumously published book has been a valuable source for our work. The book offers an account of how meanings of entities are constructed through action, through what they can do, what you can do to them and what they are made of. Rosch, E. and Lloyd, B.B. (1978) Cognition and Categorization. New Jersey: Lawrence Erlbaum. This book is important as an early source of the idea that human categories

of physical things are based on prototypes rather than on necessary and sufficient conditions. This makes space for reasoning by similarity, analogy and metaphor. Schank, R. (1986) Explanation Patterns. New Jersey: Lawrence Eribaum Associates. From a cognitive science perspective, Schank attempts to see how the creative making of an explanation could be done mechanically, and in the process furnishes a variety of concepts which are useful in analysing explanations. He offers useful ideas about different levels of need for explanation, and a

point of view in which explanation and memory are linked as driven by failures of expectation. Sinclair, J. Mc.H. and Coulthard, R.M. (1975) Towards an Analysis of Discourse. London: Oxford University Press.

An early and influential example of analysis of classroom discourse, which happened to be based substantially on lessons in science. It introduces the 'question—response—evaluation' triad. Sutton, C. (1992) Words, Science and Learning. Buckingham: Open University Press.

In this book, Clive Sutton continues and develops his previous work on language in science. He chooses to focus on words, and at this simple level, brings out the rich and imaginative substructure that scientific terms carry. The book pleads for a much stronger focus in science education on imagination and interpretation. Vosniadou, S. and Ortony, A. (1989) Similarity and Analogical Reasoning, Cambridge: Cambridge University Press. This collection of articles on metaphor and analogy ranges widely over the cognitive disciplines, and offers a variety of interesting, often incompatible, points of view.

66 DNA, 138 14, scientific,

45 14, definition, 72 C., Darwin,

144 analysis,

discourse 39—42 3, system, digestive 120—6 39, 24, digestion, 90 diffusion, 138 of, determinants situational

83 similarity, and 8

semiotic,

22 power, of 20—2

opinion, of

138 22, knowledge, of 22 interest, of 137 130, 36, 35, 30—3, 11, 8, creating, 134 124, 20—38, 17, 11—13, 4, difference, 101 71, 61—6, transposition, didactic 14 describing, 42—5

89 transformed, 89 88, 84—5, theory, and 88 actions, of pattern and 81 signs, meaningful and 78 imaginary, 86 of, aspects dangerous 84 wrong, go cannot 81 apparatus, and 87 of, structure affective 140 137, 132, 77—95, 67, 29, 15—17, demonstration,

145 tradition, constructivist 59 learning, and 103 explanations, of 140 137, 134, 44, 43, 39, 14, entities, of

construction 91 30, computer, 134 polyphony, as 135—6 multi-modal, as 143 139—40, of, modes 136 gesture, and 136 of, theories current 135 transformative, active, as 141 action, as

communication 56 change, chemical

144 B., Bernstein, 79 F., Bacon, 137 135, 118, 72—6, 70—1, 58, 43, 15, 7, 4, analogy, 82—8 75, metals, alkali 46 43, activities, 7 by, played role 93 15, meaning, and 129 in, terms new grounding 141 communication, and

action

INDEX

INDEX

Edwards, D., 8 entities, 14, 17, 39—57 and change, 45 classes of, 55 co-constructed, 50 conceptual, 53

constructing, 8, 13, 17, 48, 90 construction of, 14, 39, 43, 44, 49, 134 construction of meaning for, 52 existence of, 44 formal, 11 general class of, 55 imagined, 11 material and abstract, 49 meanings of, 7, 136 modified, 42

and 'ontological zoo', 49 physical, 53 as resources, 51 theoretical, 83 unfamiliar, 13

evolution, theory of, 72 expectations, 33, 37, 137 counter, 30—1, 89, 91

students', 30 theoretical, 89 experiment and demonstration, 80 explaining acts of, 17 art of, 2 common language for, 2 intangible things, 112—14

a phenomenon, 48, 112 and science teacher, 2, 104—8 scientific explanations, 37 as special vision of the world, 130 styles of, 8, 18, 116—33, 137 explanation(s) of carbon dioxide, 54, 106 complete, 108 of concepts, 45

and content, 96 and conversations, 12 create the need for, 4 everyday, 12, 13, 40 language for describing, 8, 136 large scale, 4, 101 of light, 36, 53 of material things, 45 motivating, 35 nature of, 40 need for, 134 and on-going interaction, 96 orchestrating, 16, 17 partial, 50, 108 plan, 17 publicly available, 72 and questions asked, 131 recognizability of, 105 scales of, 126

151

scientific, 9, 10, 11, 13, 58, 136 structures of, 5, 96—7, 99, 126 subsidiary, 4 and teacher, 96 uniform account of, 46 of weathering, 55 working towards, 117 explanatory contexts, 139 iceberg, 65 resources, 106, 108 structures, 96—7, 101, 103—4, 106 eye, 32, 74

Faraday, M., 77, 112, 114 Garcia, R., 7, 8

graphs, 30

Halliday, M., 7, 8, 144 hormones, 50, 73 Hymes, D., 144 ideology, 68, 70 interaction, 18 interest bodily functions, 24 and motivated metaphor, 74 'natural', 28 joints, 5, 31, 117—20 knowledge background, 103 common-sense, 58

embedded in stories, 66 everyday, 12 'school', 58 scientific, 12, 14, 58 and teaching, 59 transformed, 59, 89, 103 transformation of, 4, 14, 140 transforming, 9, 14, 58—61, 64, 134, 137 versioned form of, 61, 137 Labov, W., 144 language in classroom, 13 and communicating, 144 constancy and change, 59 to describe explaining, 3, 136 of description, 141 scientific, 71 studies of, 1 for talking about explaining, 2 Lemke, J., 8 liquid, 49, 52, 71 magnetic fields, 112—14 magnetism, 29 Martin, J., 7, 8

77 62—5, waves,

142—3

141, education, science in communication, in research 141—2

24 concern, of objects 134 89—90, 64, 58—61, 15, knowledge,

101 4, representations,

transforming 130 127, 61, 17, 4, transformation, 79—80 J., Thomson, 84—5 81, 15,

theory,

129 terms, 32 30, 22, 12, 8, 4, tension, 61 change, technological

72 71, 15, 7, C., Sutton, 143 subjectivity, 96 of, influence what on effect matter subject

18 explain, to how and

120—6 116, 18, tales', of 'teller 130—3 117, 18, way', my it 'see 127—30 117, 18, way', my it 'say 117—20

128—9 54—7

rephrasing,

explanations, prototypical

91 pressure, 130—3 80, tectonics, plate 41 Piagetian, 8 7, J., Piaget, 9 a, as counts what 131 explanation, of need in

90 accountable, making

phenomenon 110 99—101, 30, 4, table, periodic 68—70 parables, 75 68—70, 26—7,

chemistry, organic

49 zoo', 'ontological 68 science, of nature

116, 18, together', through it think 'let's 138 137, explanation, of styles

120—6 66, 15,

122—3 24, telling, story 13 10, protagonists,

121 66, carrier, knowledge as 10 9, story, 137 86, 11, 9, explanations, and 67 demonstrations, and 66 15, stories, 127—30 94—5, 67, 62—5, sound, 97 system, solar 46 skeleton, 81 65, 59, sign, 41 viewpoint, 12 tension,

narrative,

67 microbes, 73—4

overt,

74 motivated,

implicit,

7

129 in, terms new grounding 7

grammatical, 11 formal, 15 dormant, 74—6 covert,

137 72—6, 70—1, 58, 15, 7, 4, metaphor, 8 N., Mercer,

140 systems, 140 of, reversal process,

81

59 made, newly demonstration, and sign meaningful

32 -tension, 109 terms, and 137 9, matter, into put 95 world, material and

65 objects, 144

teachers, science of practices of import 56 friction, semiotic 16 'seeing-as', 7 writing, 15 theories, 71 language, 59 12, knowledge, scientific 2 teacher, science education, science

action, material and

91—3

82 matter, with -making 137 3, -making,

16 matter, on

imposing

46 created, 7 of, construction 128 up, building

meaning 16 world, 143 semiosis,

1

106 respiration, thinking, 51

104 explanatory, 106 48—51, 42, 13, explanations, and

15 reality,

134 95, 91—2, meaning, and 92 communicating, and events 46 activities, 49 abstract, and

51 as, entities

resources

material 152

INDEX

H[SDLQLQJVFLHQFHFODVVURRPLQGG