ve a better division of time and also ought to finish the
course in a year. Under the individual system, the slowest diligent
children finish in 7 or 8 school months, working 4 half-hours weekly.
The fastest do it in about one third that time.

Upon receipt of 20 cents, the publishers will send a manual prepared
by the author, containing full instructions as to the organization and
equipment of the laboratory or demonstration desk, complete lists of
apparatus and material needed, and directions for the construction of
a chemical laboratory.

The latter is a laboratory course in which the children are
turned loose among all sorts of interesting materials and
apparatus,--kaleidoscope, microscope, electric bell, toy
motor, chemicals that effervesce or change color when put
together, soft glass tubing to mold and blow, etc. The teacher
demonstrates various experiments from time to time to show the
children what can be done with these things, but the children
are left free to investigate to their heart's content. There
is no teaching in this introductory course other than brief
answers to questions. The astronomy and geology reading
usually accompany the work in introductory science.

ACKNOWLEDGMENTS

To Frederic Burk, president of the San Francisco State Normal School,
I am most under obligation in connection with the preparation of this
book. His ideas inspired it, and his dynamic criticism did much toward
shaping it. My wife, Heluiz Chandler Washburne, gave invaluable help
throughout the work, especially in the present revision of the course.
One of my co-workers on the Normal School faculty, Miss Louise Mohr,
rendered much assistance in the classification and selection of
inferences. Miss Beatrice Harper assisted in the preparation of the
tables of supplies and apparatus, published in the manual to accompany
this book. And I wish to thank the children of the Normal School for
their patience and cooperation in posing for the photographs. The
photographs are by Joseph Marron.

CONTENTS

CHAPTER PAGE

1. GRAVITATION 1

1. A real place where things weigh nothing and
where there is no up or down 1

2. "Water seeks its own level" 6

3. The sea of compressed air in which we live:
Air pressure