e a constant
review of the work which has gone before, a review which nevertheless
is new work--they review the principles by giving them new
applications. Furthermore, they give the pupil very definite training
in explaining the common things around him.

For four years a mimeographed edition of this book has been used in
the elementary department of the San Francisco State Normal School.
During that time various normal students have tried it in public
school classes in and around San Francisco and Oakland, and it has
recently been used in Winnetka, Illinois. It has been twice revised
throughout in response to needs shown by this use.

The book has proved itself adaptable to either an individual system of
instruction or the usual class methods.

TO THE TEACHER

Do not test the children on the narrative description which introduces
most sections, nor require them to recite on it. It is there merely to
arouse their interest, and that is likely to be checked if they think
it is a lesson to be learned. It is not at all necessary for them
to know everything in the introductory parts of each section. If the
children are interested, they will remember what is valuable to
them; if they are not, do not prolong the agony. The questions which
accompany and follow the experiments, the applications or required
explanations at the ends of the sections, and the extensive inference
exercises, form an ample test of the child's grasp of the principles
under discussion.

It is not necessary to have the children write up their experiments.
The experiments are a means to an end. The end is the application
of the principles to everyday facts. If the children can make these
applications, it does not matter how much of the actual experiments
they remember.

If possible, the experiments should be done by the pupils individually
or in couples, in a school laboratory. Where this cannot be done,
almost all the experiments can be demonstrated from the teacher's desk
if electricity, water, and gas are to be had. Alcohol lamps can be
substituted for gas, but they are less satisfactory.

It is a good plan to have pupils report additional exemplifications
of each principle from their home or play life, and in a quick oral
review to let the rest of the class name the principles back of each
example.

This course is so arranged that it can be used according to the
regular class system of instruction, or according to the individual
sy