TO THE TEACHER 



While the organization of the text is believed to be both 

 logical and pedagogical the teacher will find no difficulty in de- 

 parting from it as desired ; we have long recognized that both 

 in the development of our subject and in the assignment of les- 

 sons it is unnecessary to go from page to page through a text- 

 book. Moreover, since it is necessary to base the pupil's study 

 of his textbook upon concrete observations and experiences, the 

 use of the book must be to some extent influenced by the mate- 

 rial available from time to time. 



The questions preceding the chapters offer suggestions for in- 

 dividual and joint projects of various kinds. Although they 

 often take the form of a challenge to the teacher, we should pro- 

 ceed with our work on the assumption that we and our pupils 

 are equally interested in discovering what is true and impor- 

 tant. Where individuals can give us reliable and authoritative 

 answers, the class, including the teacher, should be glad to re- 

 ceive them, although each individual, including the teacher, 

 may reserve the right to ask the informant, "How do you 

 know ? " Often we shall find that the best knowledge we have is 

 a more or less workable hypothesis ; often we shall find that 

 knowledge is still to be dug out of resistant reality; and at 

 other times we shall find that the questions are not real ques- 

 tions at all, being based on assumptions contrary to fact. 



When we come to the questions at the ends of the chapters, 

 we may treat them frankly as teacher's questions. Yet these 

 are all offered without prejudice ; that is to say, they are offered 

 without intent to impose any doctrine. Where we ask about the 

 advantage of a process or a procedure, we must be ready to con- 

 sider also the disadvantage; where we ask, in comparing, for 

 similarities, we must consider also differences; and so on. 



xi 



