XIV 



BIOLOGY AND HUMAN LIFE 



iology. Many of the high schools offer biology after general 

 science so that this material is frequently no longer necessary. 

 Where the pupils have had no such instruction, however, or 

 where it seems necessary to review, a few simple experiments on 

 oxidation and its products, on acidity and alkalinity, and on 

 the idea of chemical reaction as illustrated by various types 

 (precipitation, effervescence, color change), as well as chemical 

 tests for nutrients, for carbon dioxid, etc., may be introduced 

 early in the course (see Part I of the author's ^'Manual of 

 Suggestions for Teachers"). 



Most teachers may prefer to prepare their own instructions 

 to pupils for carrying out experiments, field observations, and 

 other projects, for keeping records of their observations, read- 

 ings, etc., and for gathering data of various kinds. Where there 

 are large classes, or many of them, it will be economical to use 

 printed manuals for students. In any case the teacher will pre- 

 pare his own lesson by making up his mind clearly in advance 

 just what he expects the pupils to get out of the lesson and what 

 methods are to be followed for reaching the goal. 



