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

New Trends in Physics Teaching IV
string, drinking straws (plastic, and preferably translucent), glass marbles, paper, a 30 cm ruler
with a channel down the centre (provided to prevent the pencil rolling off the desk), coins, a
pencil and scissors. It is a good idea to collect these simple items and keep them in a box, so that
they are easily available. In addition, the magnetism experiments require a small magnet of any
kind, and the electricity experiments some aluminium foil, and a battery or power supply.
Here is a check list of the equipment mentioned above:
paper clips
clear cellulose tape (about 12 mm)
rubber bands (7.5 cm X 2 mm)
paper or plastic cups
straws
marbles
paper
ruler
string
pencil
scissors
coins
It is common knowledge that whereas with history, geography and many other subjects, the
first course is the easiest, the first physics course may well be the most difficult in that it depends
on understanding new concepts, not merely facts. Concrete examples put in front of one can be
mentally very satisfying, and to students in developing countries, who have little contact with the
modern industrial world, this is even more important. It is well known to psychologists that
students pass through a phase where they comprehend concrete examples before they can deal
with abstract reasoning. Therefore, most of our experiments provide two approaches. The first
is qualitative, to give students who are more at home with concrete concepts, a feel of what we
are talking about. The second is quantitative, so that those who have passed beyond this stage
may understand fully the physics involved.
Students have generally absorbed the most elementary concepts of physics before they reach
the stage of this article, but it might be useful to recall them. The idea of quantity is one not
immediately evident to youngsters. If you take a sheet of paper such as this page and cut it into
ten long strips, joining them together, a youngster wil probably think there is more of it, because
it is so long. The fact that the area is independent of the length of an object (or correspondingly
the volume of, say, a piece of clay, does not depend on whether it is long and thin or short and
fat) requires considerable thought - it is not self evident, though we may think so. The area of
the paper does not change when we cut it up, however we arrange the pieces. The next step,
that the area is the product of two lengths, requires more abstract thinking. It is before and as
the student enters this abstract phase that hands-on experiments prove most useful.
The Experiments below provide a diverse selection of those we have developed. Some of them
have been published in articles in the journal, The Physics Teacher [I]. Employing games to
perform experimental physics seems to be a new idea.
The object of this article is to encourage the reader to get up, go to the larder or nearby store,
acquire the materials required and try the experiments.
Couples and torque
As an example, the first experiment demonstrates an application of couples and torque.
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