New trends in physics teaching, v.4; The ... - unesdoc - Unesco

Energy teaching in schools
Introduction
The diverse range of approaches to teaching energy in schools throughout the world as evidenced
by the collection of papers which follows suggests very strongly that there is a special difficulty
inherent in the topic itself.
As so often with words used by physicists, the word ‘energy’ had a refined, specialized meaning
when used in a scientific context which it does not have in ordinary speech. My English dictionary
defines energy as ‘force, vigour, activity’, all synonyms which do not commend themselves to
a physicist. In such cases, it is very tempting indeed to point this out to the children and to start
with a definition. But that step itself may lead to even greater problems than the one it sets
out to cure. Consider the very common ‘energy is the ability to work’. What can the beginner
with an open mind make of that? And how does his teacher respond to the obvious question
about the meaning of ‘work’? James Clerk Maxwell had a much more graphic phrase when he
talked of energy as ‘the go of things’.
The truth is that the energy idea is not an obvious one. The concept itself came very late. It
arose from the many experiments performed by distinguished physicists between, say, 1798
when Rumford bored his cannon and the 1840s when James Prescott Joule was determining
the so-called ‘mechanical equivalent of heat’ by so many different methods and when Hermann
Helmholtz formulated the Law of Conservation (1 847). Entropy followed closely (1850). Ideas
which arise so late in the history of a science always have inherent difficulties. And it is not hard
to see why this is so. Energy cannot be seen; it cannot be heard; it cannot be felt. Indeed we can
only detect it when it is undergoing some transformation or other. What is light? Energy in
transit. What is heat? Energy in transit. What indeed is work? Energy in transit.
If, as teachers, we believe that a child’s understanding of an idea comes through the use of that
idea and that understanding grows through application, we must reject the adult, formalized
approach which takes its starting point in a definition. And then we can introduce the idea very
much earlier. Hence many present-day approaches introduce the topic of energy to children in
the primary schools and so provide a firm basis in experience on which later formalized teaching
may build.
Even this does not rid us entirely of difficulties at the later stage. One recalls arguments about
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