X TO THE TEACHER 



determined in advance, with the amount of credit to be given 

 for its satisfactory completion, most pupils need no further 

 stimulus to study. 



The practicability of the experiments outlined has been 

 demonstrated repeatedly by classes of beginning high school 

 pupils working for themselves in an ordinary school-room 

 equipped only with water and gas. A shelf should be provided 

 for the few articles of glassware, reagents and other chemi- 

 cals needed, and each student should be required to return 

 each article to its place after use. The questions have been 

 numbered to facilitate reference to them and the work may 

 thus be abridged or expanded at any point. Throughout the 

 course, the best results will be secured if the student is en- 

 couraged to investigate each subject further by consulting 

 dictionaries, encyclopedias, and other text-books, and by 

 discussing the questions with classmates, parents, and 

 teachers. 



