x A UTHOR'S PREFA CE 



Guide in Physical Nature-Study already published. There are 

 introduced into this book some things more profound than most 

 grade children will undertake to understand. They are intended 

 to serve as a background for parent and teacher in order that 

 they may present the materials to the children in better perspec- 

 tive. They are suggested by the types of questions experience 

 has shown are most frequently asked by those preparing to teach 

 this subject-matter. 



ELLIOT R. DOWNING 



THE UNIVERSITY OF CHICAGO 



THE SCHOOL OF EDUCATION 



May i, 1924 



