RELATION TO GEOGRAPHY AXD ARITHMETIC. 291 



mon earth materials, the most abundant rocks, sand- 

 stones, shales, limestones, granites, and to investigate 

 to some extent their formation. From the common 

 earth-forming rocks and minerals we can gradually pass 

 to those of great economic importance, such as coal and 

 iron ore, and thus aid in the study of economic geog- 

 raphy. 



In connection with the work in geography or nature 

 study the children should give some attention to the 

 changes in the aerial envelope of the earth. In the 

 upper grades it is most helpful to have the pupils, in- 

 dividually or collectively, keep, on blackboard or on 

 blanks, a record of the temperature, height of barom- 

 eter, presence of frost or dew, direction and force of 

 wind, cloudiness and rain or snowfall. In connection 

 with this there may be some study of the daily weather 

 maps, which can be obtained free by any school from 

 the nearest station of the Weather Bureau, or from the 

 office at Washington. 



In the upper grades the work must be related more 

 and more closely and directly to man. As political 

 geography, or the earth as the abode of man, becomes 

 more important, we shall find most helpful in geography 

 a knowledge of those forces by which man has subdued 

 the earth, of those minerals which he has found most 

 useful, of the plants and animals which most aid in 

 man's development, and of the uses man has made of 

 forces, minerals, plants, and animals. 



Hence the study of physics and chemistry, and the 

 intensive study of such minerals as coal and iron, be- 



