SECOND GRADE FALL WORK 87 



understand that commerce is a means for the interchange of 

 useful products, and that the profits of the merchants usu- 

 ally are just and reasonable. 



The play store already described may serve a very useful 

 purpose in all the lower grades. It may be conducted by 

 the pupils in each grade, in turn, to suit the convenience 

 of the work. 



LESSON X 

 CHANGES IN TEMPERATURE 



What part of the day is coldest ? What part is warmest ? 

 Why is it warmer near noon than in the morning or evening ? 

 Use a shadow-stick, and note, the length of. its shadow in the 

 morning, at noon, and at night. 



Light and heat come together to us from the sun. When 

 the shadow is long, the heat contained in the sunbeam 

 obstructed by the upright would fall on how much space if 

 the upright were removed? At noon, when the shadow is 

 short, the heat from a like beam would fall on how much 

 space if the upright were removed? Account, then, for 

 the greater heat at nqon. 



Give other illustrations of the greater heat in direct than 

 in slanting rays. Which is stronger, a direct or a slanting 

 blow ? When reading in a dim light, how do we hold our 

 book to see best ? Why ? What part of an object standing 

 near a fire gets hot first ? Why ? On which side of the 

 schoolhouse do the boys congregate on a cold day? How 

 do the sun's rays strike this side? How do they strike the 

 other sides? 



What change of temperature occurs as we ascend a moun- 

 tain ? Where does the snow melt first, in the valley or on the 



