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

String and tape experiments
the other. Not all children are so combatively inclined, however. As a result, games have been
devised which allow for a spirit of co-operation without the concomitant aggression. One such
is the lap game [3, p. 1721 . In this, the group forms a circle, and each individual sits on the lap
of the individual behind. The world record used to be 1500 lap-sitters. Of course, if one person
falls over, a co-operative effect - essentially a soliton wave of non-lap-sitters - moves around the
circle. The speed with which this occurs, though not equal to the speed of sound, is nevertheless
very rapid. Many such games can be devised to demonstrate physical principles. In a large class,
interaction on a personal basis, not merely between the teacher and the student, but also between
the students themselves, is virtually nonexistent. Furthermore, such large classes are given, more
often than not, in vast auditoria not designed for physics use, where there are no apparatus
storage facilities, and it is difficult for the students at the back to see. The difficulties of interesting
the students in the course can be greatly facilitated by involving them directly in demonstrations.
For example, the students can be invited down to the podium to demonstrate gas
kinetic theory. A few of them mill around, bumping into one another, pretending they are ‘gas
atoms’. This contact sport is evidently much appreciated by the students, provided it is not
carried too far. More students come down, making closer contact, hands on shoulders, but breaking
away to put hands on the shoulders of different students to form a liquid. Then, they put
hands on the shoulders of the nearest individual and stick - a solid. Such simulations:
1. wake up the students
2. act as demonstration experiments
3. require no setting-up time or equipment
Acting out really drives home the point.
I hear and I forget. I see and I remember. I do and I understand. (Chinese proverb)
Of course, the question arises as to how much is physics and how much game, but such experiments
seem an excellent idea in moderation. Which type of physics lends itself to such methods?
People are particles, so clearly gas kinetic theory is suitable - and in fact, many quantum
phenomena can also be described (short of tunnelling through a potential wall). Here are some of
the ideas we have tried out, together with the principles which they aim to demonstrate.
Pirates treasure game (vectors)
It is notorious that pirates always bury their treasure beneath some beach on a desert island, and
then provide a nearly incomprehensible map to find it. The object of this game is to provide a
suitable vector description for finding the treasure, using paces as the unit of length. It should be
remembered that the pace was the unit employed by the Romans, whose professional pacers’ sole
job was walking between towns to measure the distance. So we can start by saying ‘take three
paces north (or towards the blackboard, or whatever) and four paces west. Count the paces
directly back to where you started (which would be five) and continue beyond by the same
number’ --until you arrive at the desk with the treasure in it. The aim is to combine distances
vectorially and reach the point where you wish to go.
The three-metre dash (kinematics)
To emphasize the difference between velocity and acceleration, we have two races - one a dash
of three metres, and the other a more normal length up to 50 metres, or whatever is available.
The students who accelerate most rapidly are not necessarily the ones who can do well over
distance. Stamina plays no part here - it is inertia which counts.
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