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

New Trends in Physics Teaching IV
The students were asked to choose and develop an experiment and to prepare a lesson along
lines which wil be familiar to teacher trainers. They considered what particular benefits the work
offers (the aims) in terms of the processes of science (definition of problem, skills developed,
design, choice, reporting, etc.), in terms of the learning of subject matter (absorption of radiation,
optics, etc.) and in terms of social relevance (contribution to energy in the home, awareness of
economic significance, etc.). They prepared introductions, presentations and questions. It was
pointed out that solar experiments often take a long time and that the boys and girls must be
kept occupied whilst the experiment proceeded. We are not keen on stereotyped worksheets
which need only a few words to be written or deleted so a variety of activities was called for.
Wherever possible, frequent involvement with the apparatus was arranged. The best experiments
were those where adjustments had to be made frequently or where a series of readings (usually
of temperature and time) were called for. Otherwise boys and girls were asked to draw the
apparatus, label a diagram, refer to books or offprints, make notes on the experiment or to
discuss with a teacher what was happening. Table 1 is a list of the experiments attempted. Brief
notes on some of them are included at the end of this article.
Most of the experiments worked. One or two did not. The ‘camper’s water heater’ - a concoction
of hosepipe, polythene and a plastic bucket - resolutely refused to thermosyphon, but the
level of involvement of the children in constructing and adapting the system fully justified its
inclusion. At the outset I was sure that the solar oven was badly designed and would never cook
anything. Again, its very inadequacies challenged many members of the group to improve it.
The level of invention on the part of the children was remarkably high and the feeling of success
when an egg was finally cooked justified the time that had been taken. The washing-up bowl
mirrors (see below) leaked and the radius of curvature of the surface slowly increased. But this
was turned to good effect. As the focal length changed, so the children had to increase the
distance between the mirror and the can that was being heated. They learned in an active way
that the curvature and focal length are intimately connected. We still have not solved the sealing
problem, but the mirror is so good that it is one of our greatest successes - and the vacuum
holds long enough for the mirror to be used throughout a double period.
Overall the attempt to introduce a practical study of solar energy into a school curriculum
was entirely successful. The attitudes of the university students were changed and many of them
have continued to work with solar energy in their own schools. The children enjoyed working
in the sunshine at problems which had a practical application. School staff from many different
disciplines stopped to have a word about progress and we even picked up one very enthusiastic
girl who should have been at lessons elsewhere. One big problem which arose was storage of
apparatus. Space is not plentiful in school laboratories. The apparatus could not be left outside
overnight for fear of damage and the temporary storage in the school hall was unsatisfactory
as a long-term measure. As our apparatus has developed, so it has got smaller. There is no need
to have many square metres of surface and many litres of water. Effects are often observed more
quickly on a smaller scale and the storage problem is eased. The children we worked with were
not examination candidates in physics so we were free to use time as we wished, unrestricted
by demands to get through a syllabus. Even so, we felt that the work related so well to ‘0’ level
and CSE examination syllabuses that time in the sunshine for even these candidates would be
well spent.
A further problem was pointed out by the students. Working with four or five children is easy.
The organization of a whole class in the hands of one teacher would be much more difficult.
The distribution and erection of apparatus would need to be very carefully controlled and the
scheduling of work would need to depend far less on the continuous presence of a teacher.
Perhaps more detailed worksheets would have to be written or the variety of activities would
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