SELECTION AND SEQUENCE OF MATERIAL. 307 



Later, the study of minerals and rocks of economic 

 importance, such as graphite, gypsum, pyrite, sulphur, 

 of coal and of the iron ores, will be an excellent 

 preparation for economic or commercial geography. 

 Hundreds of minerals valuable to the collector and 

 mineralogist on account of their rarity, are of no value 

 in nature study in the schools, for the very reason that 

 they are rare. 



The selection of material for plant and animal study 

 in the earlier years is largely determined by higher 

 aims. During the later years of the course, utilitarian 

 considerations must have more influence, and will lead 

 to the choice of material of economic importance which 

 will aid in the geography work : the grains, wheat, corn, 

 rice, and their products; the fruits, apples, oranges, 

 lemons ; the cotton and flax plants, and the manufac- 

 ture from them of cloth ; the animals and animal prod- 

 ucts of greatest economic importance and most commonly 

 referred to in the work in commercial geography. 



In this way nature study will be an aid in physical 

 and commercial geography. Man study, history, and 

 related literature may be made equally helpful in po- 

 litical geography. 



In considering the question, The study of what 

 material will give the knowledge most helpful in sub- 

 sequent science work? we will see the importance of 

 selecting for study material which is typical of large 

 classes or groups, and phenomena which illustrate, and 

 prepare for an understanding of principles. 



