X. THE ECONOMIC RELATION OF GREEN PLANTS 



TO MAN 



Problems. — How green plants are useful to man. 



(a) As food. 



Q)) For clothing. 



(c) Other uses. 



Row green plants are harmful to man. 



Suggested Laboratory Work 



If a commercial museum is available, a trip should be planned to 

 work over the topics in this chapter. The school collection may well 

 include most of the examples mentioned, both of useful and harmful 

 plants. 



A study of weeds and poisonous plants should be taken up in 

 actual laboratory work, by ooUeotion and identification, or by demon- 

 stration. 



To THE Teacher. — This chapter, which is intended to sum up the preceding 

 chapters from the practical aspect, may be made largely in the nature of reading 

 and reports. It is wise when teaching a course in biology (or any other subject) 

 to vary the work as much as possible, both to maintain interest and to prevent 

 stagnation of thought on the part of the pupil. 



Problem 85 : To determine the economic importance of some 

 green plants. 



Materials. — Toothaker's Commercial Raw Materials is an 

 invaluable reference book for this exercise. This might well be 

 planned for a field and museum trip to some commercial museum, 

 or the school museum may be used. Also visit the public or pri- 

 vate markets in your locality and list all the food plants or their 

 products used for food. 



Method. — Fill out a table hke the following. 



Conclusion. — In what ways are green plants useful to man? 



106 



