xtent
appeal to children. These questions in effect state the problems which
the section helps to solve.

Following the questions are some introductory paragraphs for arousing
interest in the problem at hand,--for motivating the child further.
These paragraphs are frequently a narrative description containing a
good many dramatic elements, and are written in conversational style.
The purpose is to awaken the child's imagination and to make clear the
intimate part which the principle under consideration plays in his own
life. When a principle is universal, like gravity, it is best brought
out by imagining what would happen if it ceased to exist. If a
principle is particular to certain substances, like elasticity, it
sometimes can be brought out vividly by imagining what would happen if
it were universal. Contrast is essential to consciousness. To contrast
a condition that is very common with an imagined condition that is
different brings the former into vivid consciousness. Incidentally, it
arouses real interest. The story-like introduction to many sections is
not a sugar coating to make the child swallow a bitter pill. It is
a psychologically sound method of bringing out the essential and
dramatic features of a principle which is in itself interesting, once
the child has grasped it.

Another means for motivating the work in certain cases consists
in first doing a dramatic experiment that will arouse the pupil's
interest and curiosity. Still another consists in merely calling the
child's attention to the practical value of the principle.

Following these various means for getting the pupil's interest, there
are usually some experiments designed to help him solve his problem.
The experiments are made as simple and interesting as possible. They
usually require very inexpensive apparatus and are chosen or invented
both for their interest value and their content value.

With an explanation of the experiments and the questions that arise,
a principle is made clear. Then the pupil is given an opportunity to
apply the principle in making intelligible some common fact, if the
principle has only intelligence value; or he is asked to apply the
principle to the solution of a practical problem where the principle
also has utility value.

The "inference exercises" which follow each section after the first
two consist of statements of well-known facts explainable in terms
of some of the principles which precede them. They involv