Preface vii 



effect state the problems which the section helps to 

 solve. 



Following the questions are some introductory para- 

 graphs for arousing interest in the problem at hand, 

 for motivating the child further. These paragraphs are 

 frequently a narrative description containing a good 

 many dramatic elements, and are written in conversa- 

 tional style. The purpose is to awaken the child's im- 

 agination and to make clear the intimate part which the 

 principle under consideration plays in his own life. When 

 a principle is universal, like gravity, it is best brought 

 out by imagining what would happen if it ceased to exist. 

 If a principle is particular to certain substances, like 

 elasticity, it sometimes can be brought out vividly by 

 imagining what would happen if it were universal. Con- 

 trast is essential to consciousness. To contrast a condi- 

 tion that is very common with an imagined condition that 

 is different brings the former into vivid consciousness. 

 Incidentally, it arouses real interest. The story-like 

 introduction to many sections is not a sugar coating to 

 make the child swallow a bitter pill. It is a psychologi- 

 cally sound method of bringing out the essential and 

 dramatic features of a principle which is in itself interest- 

 ing, once the child has grasped it. 



Another means for motivating the work in certain 

 cases consists in first doing a dramatic experiment that 

 will arouse the pupil's interest and curiosity. Still an- 

 other consists in merely calling the child's attention to 

 the practical value of the principle. 



Following these various means for getting the pupil's 

 interest, there are usually some experiments designed to 



