238 METHODS IN TEACHING 



by rain and other actions of water; the effect of lateral 

 pressure on the crust of the earth is easily presented by 

 putting differently colored soils with layers of salt or some 

 other white substance between them on a large blotting pad 

 slightly raised in the center. Apply lateral pressure gently 

 until the uppermost fold breaks. 



Several careful experiments are made so that the chil- 

 dren may understand the action of air. This is very inter- 

 esting to the pupils and is preparatory to 

 of ^ the study of climate in later grades. For 



one of these experiments a short section of 

 gas pipe is filled with water, the caps are screwed on se- 

 curely, and the pipe is placed in a bucket and surrounded 

 with a mixture of salt and ice. The children watch the 

 formations that appear on the outside of the pipe, dew, 

 frost, and ice, where a few drops of water have been placed 

 on the outside. After a while the pipe bursts by the ex- 

 pansion of the water as it turns to ice. A thermometer 

 placed in the bucket adds to the interest in the experiment. 

 Valleys are treated in connection with rivers, several 

 weeks being devoted to the related subjects. Sandbars 

 formed in a river, channel, or creek are 

 and Rivers good examples of the work of a river. 



Several land and water forms are learned 

 through the study of ponds and lakes. These are distin- 

 guished, named, and drawn by the pupil, who is led to form 

 his own definitions. As new places are mentioned they 

 are looked up on the map in the text-book, then on the 

 wall map, if possible on the globe as well. The habit of 

 locating a new place is to be classed with looking up a new 

 word. 



