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

Senegal
Reflection on current trends in physics teaching in upper
secondary education and the first years of university
education in Senegal: the teaching of the concepts of energy,
entropy and irreversibility
D. FALL.
A survey conducted among teachers and other education personnel in Africa would reveal that
pupils encounter three major difficulties in assimilating certain physics concepts: first, the
expression of these concepts in a foreign tongue; second, the lack of material facilities for the
experiments which so often serve as an indispensable means of illustrating them; and third, the
teaching methods which often lead the pupil to recite set formulae and even to describe experiments
without having really understood the physical reality to which they refer, the meaning of
the words used or the formulae quoted.
In the case of Senegal, efforts have been made in the last few years to improve such teaching
and an experiment is being carried out in pilot schools where new physics courses are taught in
the sixth form. A good start must be made if pupils are not to go on to university still suffering
from inadequacies.
The present paper is mainly concerned with this sixth-form course and with the steps that
should then be taken to ensure some continuity in this teaching thereafter, with particular
reference to university education (first and second years).
THE CONCEPT OF ENERGY
The concept of energy is gradually built up on the basis of the concept of the capacity for work
of a force, with reference to experiments involving the operation of simple and easily constructed
machines: the slow fall of a mass, the stretching of a spring, the lifting of a solid body, the
rotation of a solid about a fixed axis, etc.
Work, together with all the other concepts used to interpret physical phenomena, is expressed
by a simple mathematical formulation: if the application point of the constant force F moves
from A to B, the work W is expressed by the scalar product W = F X AB; and the elementary
work for a displacement 6s, by W = F X 6s. This, of course, pre-supposes a knowledge of basic
mathematics, but the main point is that each formula should have a physical significance without
which the pupil cannot grasp the physical reality that the teacher is seeking to convey which is
what really matters. I personally have seen on pupils’ exercise sheets simplifications introduced
129