TO THE TEACHER XV 



Value of Demonstration. The good teacher will always demonstrate 

 everything possible. It will be especially necessary for the teacher to 

 give to students who have not studied plant life good demonstrations of 

 the facts learned in that study, which this book assumes all students to 

 know. For instance, if the students do not already know them well, the 

 teacher should show them every part of all the plants studied, and tell 

 the name of each part and what it does. There are concise definitions 

 in the glossary, which will be helpful in this work, both to student and 

 teacher. But no good teacher will leave students to learn the use of 

 many words, or expect them to acquire a knowledge of the structure of 

 plants, or of the parts of plants, from such a condensed treatment as is 

 possible in this glossary or in the body of the book. 



Tools. The use of tools cannot be taught by a book. If the school 

 has tools, a book is not needed to teach what is most important about 

 their use. And if a school is without certain tools, a book will certainly 

 do no service by devoting much space to describing them and explaining 

 their use. 



