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Research In Science Education, 1987, 17, 31-37.

THE MATTER OF ENERGY

Malcolm Carr, Valda Kirkwood and Barry Newman

INTRODUCTION: PROBLEMS

The Learning in Science Project (Energy), undertaken by the-Science Education

Research Unit of the University of Waikato - Hamilton Teachers College, New Zealand,

has made us painfully aware of an issue which teachers constantly face: how a specific

concept is to be understood. In this project, it was the concept of energy, understandably,

which claimed our attention, a concept of no little significance for science curricula.

It was cause for concern to recognise that there are a considerable number of

difficulties a~ociated with the understanding of this concept. Some of these are of a

philosophical kind while others are educational in nature. Problems of one kind frequently

entail problems of the other.

ORIGINS OF SOME PHILOSOPHICAL AND EDUCATIONAL PROBLEMS

Concepts Evolve

A ter:n such as 'energy' evolves over time. Elkana (1974) argues for the tortuous

development of an understanding of the term in a physics context in the nineteenth

century and Cohen (1974) maintains that such an understanding, in the same context, has

undergone significant revision in the twentieth.

In Different Contexts Concepts Evolve Differently

Such a term also evolves in different contexts differently. Phrases such as 'energy

budget' and 'profiles of energy distribution' in a biology context are far removed from the

'potential energy' and 'kinetic energy' ideas of classical physics. A science, technology and

society or a chemical engineering context is likely to nurture its own special brand of

energy, while d/fferent languages, and different cultures using the same language, will

presumably make their distinctive contribution to its characterisation.

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For One Person Or Context There May Be Differences

Distinctions such as 'technical vocabulary' and 'folk definitions' (Laferriere, 1987) or

other labels like 'layperson's usage', 'science teacher's usage' and 'scientist's usage', helpful

as they are, still do not do justice to the situation. For instance, such terms fail to

indicate that an individual may be inconsistent in usage and that there may be differences

of usage among those operating in the same field.

Science Teachers With Different Background May Teach Differently

Kirkwood et al. (1986) have suggested that science teachers with differing academic

backgrounds may teach about energy in different ways. A teacher with a tertiary physics

education might have a perspective on energy related to, capacity to do work,

conservation of energy, heat, mass-ener~y relationships, quantum mechanics and fields.

Biological perspectives might reflect ideas on energy related to, energy sources, energy

flow through biological systems, energy balance and energy rich and energy poor

co m pounds.

One can understand if the specialist biology teacher tends to colour his teaching with

energy flow diagrams and traces systems back to the sun. One can similarly appreciate

the physics teacher seeing 'capacity to do work' in all her carefully designed practical

activities and teaching accordingly.

How Does This Affect The Students?

What happens to students, meeting at different stages of their junior science

educational experience a variety of teachers with their different perspectives? Does an

inability to come to terms with the concept as taught by the teachers save them from

distress or do they exhibit considerable creative ingenuity in making sense out of the

potentially perplexing? Do they learn to play different games for different contexts,

particularly perhaps, as they progress to science at the senior level?

Students Already Have A Point Of View

It is now well known (e.g. Brook and Driver, 1986; Carr eta]., 1987) that students

come to the classroom with their own thoughts on the subject. Teaching that fails to take

into account students' perceptions, their use and understanding of language, and the ways

in which they are likely to respond to teacher offerings, is setting a course for educational

mishap. One would be unwise to dismiss ideas such as 'the world's running out of energy',

'fat people must have lots of energy but they don't seem to' or 'cars create energy when

they move' as of no consequence when trying to introduce the subject of energy in a

scientific context. Likewise, having concluded a unit on energy, responses from students

such as 'the light energy was stored in the battery', 'look at all that nuclear energy - the

sound, light and heat' or 'the elastic energy gets smaller because the spring gets smaller'

should cause teachers to try again.

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SOME PHILOSOPHICAL PROBLEMS

Given science education's interest in the scient if ic domain, we will res t r ic t our

discussion under this heading to this area and ignore references to energy in popular

discourse.

The 'Discovery' Of The Concept Of Energy

Elkan's account of the 'discovery' of the conservation of energy principle is a

sobering one and appropriate for setting the stage for our discussion. He maintains that

"the general concept of energy became meaningful only through the establishment of the

principle of conservation of energy in all its generality" (p. 9), "the concept of energy as

we know it today ... has emerged from Helmholtz's 1847 paper 'Uber~die Erhaltung der

Kraft' and that up till then, nobody, including Helmholtz himself, had a clearly defined

concept of energy" (p. 9) and " the very ambiguity in the word 'Kraft' (The German word

'Kraft' is usually translated into 'force' or 'strength') is indispensable for the

comprehensibility of" Helm holtz's paper (p. 17).

What Does 'Conservation Of Energy' And 'Energy' Mean?

The intricacies surrounding the development of the concept and the lack of clarity

concerning what was to be understood by 'Kraft' (llelmholtz substituted 'Energie' for

'Kraft' some years later, see Elkana, p.133) should warn us to tread carefully even today in

our efforts to proclaim what we mean by the term. Keeton (1940), almost a century after

Helmholtz's paper writes: "the theory of the conservation of energy as matter of fact, is

extremely ambiguous".

Cohen (1974) in his Foreword to Elkan's work states that the conservation of energy

principle is now known to be false. He makes this claim apparently because of his views

on energy/matter (mass?) relationships, which probably entail that mass is gained or lost

at the expense or otherwise of energy. Gauld (1984) argues that such a position is based on

misunderstandings of both energy and mass.

The Experts Don't Agree

Certainly the experts differ. Warren (1983) maintains that "energy is an advanced

abstract concept, the capacity to do work". On the other hand, Kemp (1984) argues that

the notion that energy is the capacity of a body for doing work is "misleading if not

completely incorrect". Concepts are of course what we make of them and we may argue

for the acceptability of such notions on grounds relating to, for example, increased

understanding, greater consistency or better corn municability. Schmid (1982), accordingly,

argues that energy can be understood as a primary underived physical quantity and refers

to a course based on this understanding. It is a course which involves "part of a

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restructuring of physics as a whole"- a sober reminder that no prescription for a scientific

concept is a sacrosanct.

What About Other Experts?

Furthermore, what are biologists or chemists, to make of these pronouncements in

physics? Are the physicists the only one entitled to say what energy is? Van Koevering e t

a]__.. (1987) write with ease of 'flow of energy', 'energy efficiency', and 'the conversion of

solar energy to corn and alcohol', all a far cry from 'capacity to do work', or 'internal

energy'. Though questions of the economical, productive and consistent use of the term

may always be relevant, by what criteria could we argue that biologists, as opposed to

physicists, should not develop their own conceptual networks?

The Creation Of the Energy Concept

Simply pdt, the energy concept, considered in whatever domain, is a creation and

different creators have been at work and continue to be at work with different results.

Given that all concepts are creations however, a more helpful position might be to

consider the question of the sense in which the energy concept relates to reality, give a

reality.

In What Sense Does Energy Exist?

Energy may be thought by some as existing in the way that chairs are thought to

exist. Perhaps for others it is considered to exist as love exists. For yet others it may be

thought of as a creation brought about to unify a variety of phenomena. Whatever our own

position, one can understand there being some objections to the idea that energy exists as

a moo cow exists. One could argue that energy, in a scientific context, only came into

'existence' a little over a hundred years, when its concept was created, whereas moo cows

have been around much longer than that. Conversely, it may be argued that moo cows are

easier to see but that for some time humanity has been groping about in the darkness with

a vague idea of energy in mind and only in recent times has light dawned.

Regardless of our difficulties in handling the notion of existence however, it is

another problem that energy ideas are often raised in contexts which seem to suggest no

questions about their existence or creation. Both teacher and student alike often seem to

be quite ignorant of historical processes and the part played by minds and the relevance of

both for our understanding of the type of entity that energy is or might be.

PHILOSOPHICAL QUESTIONS OF DETAIL

Contexts For Asking Philosophical Questions About Energy

When one raises philosophical questions one does so with particular contexts and

perspectives in mind. For example, from a biologist's point of view, the notions of energy

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being stored in biochemical systems and being transferred from one system to another are

likely to be seen as appropriate, whereas references to the notion of capacity to do work

are likely to be regarded as quite inappropriate. Even within specific disciplines, different

contexts may demand different perspectives.

Some Questions About Enerb=5,/

Not forgetting the problem of which perspective one wants to adopt and when, the

following issues are a small sample of the myriad which can be raised.

What is the relationship between energy and work? (Of course, this and other

questions can be rephrased in terms of what we would prefer rather than in terms of

"what is").

What is the relationship between heat transfer and internal energies?

In what sense is energy a condition rather than a process?

Should one make a distinction between mechanical energy and internal energy?

Why do we hold to the principle of conservation of energy?

What constitutes a form of energy?

What connections are there between one form of energy 'decreasing' and another

form 'increasing' in the same system?

Are such connections causal and what might we mean by causal?

What do we understand by energy degradation and how are the ideas of useable or

useful energy associated with it?

In what ways do the terms 'potential' or 'stored' assist or serve to cloud our

understanding of the concept 'energy'?

What is meant by an energy source and in what sense does energy flow?

How does one define the boundaries of one's system and what's the value of doing

this?

What do we understand by fields, energy stored in fields, equipotential line, field

strengths and field lines?

Such ques t ions s e rve to give us some idea of the c h a r a c t e r of the m o n s t e r t h a t

r e s i de s wi th in our s c i e n t i f i c and e d u c a t i o n a l house.

A Few Ideas

A few corn m e n t s on such issues:

(i) T h e r e could be some value in he lp ing s t u d e n t s to r e c o g n i s e e n e r g y fo rms as

p h e n o m e n a with which we a s s o c i a t e ene rgy , r a t h e r than types of ene rgy .

(ii) If s t u d e n t s a re to be i n t r o d u c e d to p o t e n t i a l and k ine t i c e n e r g y types , i t migh t be

of some value to i n d i c a t e t h e i r s i m i l a r i t i e s and d i f f e r e n c e s . Both types a r e

36

(iii)

(iv)

(v)

analysed with reference points in mind, but one type is associated with movement

while the other is not, though changes in the other will involve movement.

It might be helpful to associate changes in kinetic energy with changes in

'quantity' (the sound died away, the car accelerated), whereas changes in potential

energy could be associated with changes in 'appearance' (the nuclear or chemical

materials have altered, the magnets are closer together).

It might also be helpful to realise that while it may be easy to recognise that

kinetic energy has increased or decreased, it may be very difficult if not

impossible, at first glance to appreciate whether potential energy has changed at

all. One may need to know the conventions that apply to various situations or one

may need to have access to certain otherwise obscure empirical data and even

then, only an appeal to conservation of energy may help.

There is something odd about an entity which can 'exist' as being two types,

kinetic and potential (internal energies being reduced to these), being conserved.

Being of two types is suggestive of the entity having too much flexibility for

conservation to apply. The flexibility is lost however, if one type inexorably

follows the other as night follows the day. The extent to which the two can be

tied together depends upon one's creativity and choice of models when analysing

phenomena such as collisorks or light emissions. Are these ideas helpful

educationally?

CONCLUSION: SO WHA~S THE MATTER?

Is 'energy' the worst of those concepts with which we have both educational and

philosophical concerns? Who knows? Regardless, our sympathy to those involved in

associated research and a warning to tread cautiously in other areas. 'Energy' today,

'space', 'time' and 'matter' tomorrow.

REFERENCES

BROOK, A. & DRIVER, R. (1986) The construction of meaning and conceptual change in classroom setting: case studies on energy. Leeds, Centre for Studies in Science and Mathematics Education, The University of Leeds.

*CARR, M., KIRKWOOD, V., NEWMAN, B. & BIRDWHISTELL, R. (1987) Energy in three New Zealand secondary school junior science classrooms. Research in Science Education, 17___, 117-128.

COHEN, I. B. (1974) Foreword in ELKANA, Y. The discovery of the conservation of energy. London, Hutchinson Educational, pp. vii-x.

37

ELKANA, Y. (1974) The discovery of the conservation of ener{~. London, Hutchinson Educational.

GAULD, C. (1984) Conservation of mass and energy in high school science. Australian Science Teachers Journal, 30 (2), 34-40.

KEETON, M. T. (1940) Some ambiguities in the theory of the conservation of energy. Philosophy of Science, 8__, 304-319.

KEMP, H. R. (1984) The concept of energy without heat or work. Physics Education, 19 (5), 234-239.

KIRKWOOD, V. M., CARR, M. D., BELL, B. McCHESNEY, J., OSBORNE, R. J. & SYMINGTON, D. (1986) Learning in Science Project (energy). Lab Talk, 30 (5), 7-11.

LAFERRIERE, J. E. (1987) Folk definitions influence the acceptance of technical vocabulary. A,n erican Biolog~ Teacher, 49 (39), 149-152.

SCHMID, G. B. (1982) Energy and its carriers. Physics Education, 17(5), 212-218.

VAN KOEVERING, T. E., MORGAN, M. D. & YOUNK, T. J. (1987). The energy relationships of corn production and alcohol fermentation. Jou,'nal of Chemical Education, 64 (I), 11-14.

WARREN, J. W. (1983) Energy and its carriers: a critical analysis. Physics Education, 18 (5), 209-212.