58 TEACHING SCIENCE IN THE ELEMENTARY SCHOOL

is avoided in the primary grades. Care should be taken to as-
sure the authenticity of the model, a too often neglected feature.
Good working materials for pupil-made models are soap and
clay.

Experimenting as a Means of Learning.
 Experimenting has many values for science instruction.
First, experimenting offers the opportunity for children to
learn by doing, an often repeated principle in education which
is not always given a chance to function. Second, experimenting
is vivid and convincing. "Seeing is believing", in most situations
and for most youngsters. Third, through the actual use of ma-
terials and procedures that can be repeated or verified, children
are led to see the need for eliminating sheer guessing or argu-
ment as a basis for opinion. They often make the discovery they
must change an opinion in the light of the evidence there before
their eyes. Experimenting is a major factor then, in developing
a scientific attitude as well as in acquiring the use of elements
of the scientific method. Fourth, it encourages the exercise of
imagination and creative effort. It opens up opportunities for
subsequent individual investigations, the results of which can
be shared with the group.
 The following principles are important in planning for ex-
periments if the work is to be meaningful and effective:
 A. Experiments should be conducted in such a way as to
cause pupils to think. An experiment in which the teacher does
and tells everything offers little challenge to the thinking of
the pupils.
 B. Children should be fully conscious of the purpose for
performing the experiment. It is never safe to take this aware-
ness of purpose for granted. The purpose should be stated in
several ways if possible and it is often desirable to write it on
the board in a simple, direct form.
 C. Careful planning is essential to successful experiment-
ing. A plan of procedure must be set up, appropriate materials
must be assembled, by the children as far as possible, and then
the plan must be followed accurately to insure that the results
can be depended upon.
 D. For the most part children themselves should perform
the experiments. It is interesting to note that all recently pub-
lished science texts address the experiments to the children and
that the illustrations show pupils, not teachers, performing the
experiments. Children benefit not only from the actual doing
and the close observation but also from the opportunity to as-
sume and discharge responsibility in a real situation.