PREFACE V 



Earth's Crust there is an added topic, The Earth in Rela- 

 tion to other Astronomical Bodies. Considerable new mate- 

 rial on nutrition and proper care of the human body is added. 

 Particular attention has been given to relations which the 

 studies bear to household problems as well as to those of the 

 community and of the industries. At the beginning of each 

 chapter a list of Questions for Discussion is given. It is 

 expected that when beginning the work of each chapter the 

 pupils and teacher will read and discuss the questions briefly. 

 These questions recall pupils' previous experiences and set 

 up new problems whose brief consideration gives significant 

 purpose to the text and experimental work which follows. 

 After the chapter has been studied, the questions provide 

 the best means of review. About fifty additional illustrations 

 are included. 



Throughout the course there should be experimental work 

 in the form of demonstrations, individual or group laboratory 

 exercises, and home or school projects. A laboratory manual 

 has been prepared to serve as a guide in the performance of 

 experiments and demonstrations. The apparatus for use in 

 experiments should be the most simple available, and that 

 from the community or home may often be more educative 

 than complex and costly apparatus. 



The authors wish to express their appreciation for most 

 helpful advice, suggestions, and criticisms given by Director 

 Charles H. Judd, Principal F. \V. Johnson, and Mr. Charles 

 J. Pieper of The University of Chicago School of Education. 

 In the revision Professor Allan W. Abbott of Teachers 

 College, Columbia University, has read the entire manu- 

 script to correct and improve it in English form and style ; 

 Director Alice F. Blood and Professor Ula M. Dow of the 

 School of Household Economics of Simmons College have 

 added much to the household applications of the course ; 

 Professors E. B. Frost of the Yerkes Observatory and 



