iv PREFACE 



enough to rule the body. This desire will be created by the 

 material in the first few chapters if the teacher is of the proper 

 character. Enough material is presented to give the pupils 

 sufficient knowledge and wisdom so that they may know how 

 to protect themselves. 



Second. A logical method of thinking is developed, so that 

 the pupils have a mind open for the consideration of new facts 

 and principles, thus relieving them of some of their supersti- 

 tions. Pupils who are taught in a logical manner soon form 

 logical habits of thinking and become able to judge with an 

 accuracy that will surprise many teachers. 



Third. A desire for more knowledge and further scientific 

 study is created. The fundamental principles underlying scien- 

 tific knowledge are gradually developed and appear in new forms 

 in various places with new applications. There are sufficient 

 repetitions of the fundamental facts to make the learner thor- 

 oughly familiar with them so that he can use them, thus giving 

 him confidence in himself. Self-confidence of the right sort is 

 an absolute necessity on the part of a learner. The author would 

 like to suggest that teachers give a review at the close of each 

 long chapter and also at the close of a number of chapters on 

 related material. Repetition of fundamentals until they actually 

 become a part of the pupil is a secret of successful science teaching. 



The material which touches upon the pupils' personal habits 

 is placed as early as possible in this course, so that they can 

 use it at the beginning of their high school course and form 

 proper hygienic habits before the four years are passed. The 

 elementary chemistry is placed early in the course in order that 

 a better understanding of the following matter may be had. 

 In connection with chemistry it is not difficult to get an idea 

 of an atom and a molecule. These ideas are fundamental to 

 the study of all scientific subjects and are necessary for a respec- 

 table understanding of the chapters that follow A few chemi- 

 cal symbols have been introduced to give the pupils an idea of 

 the composition of matter. Most pupils have a desire to know 

 the symbols of many common substances. Sufficient material 



