'174 NATURE STUDY -BY GRADES 



be irrigated. When and why do they need thinning? Why 

 not plant fewer seeds and avoid the work of thinning? De- 

 scribe the care and harvesting of the crop; the care given to 

 those beets which are left to produce the seeds. How is the 

 best seed procured ? 



An explanation of the different processes of making sugar 

 should follow, providing the children can visit a sugar fac- 

 tory, but a verbal description alone will do little good, and 

 if given at all, should be brief and general. 



LESSON XLVII 

 CARE AND CONDITION OF THE SOIL 



Dig a hole in the ground and collect from various depths 

 samples of soils, and place them in proper order in a glass 

 bottle. Why is the top soil of darker color than the sub- 

 soil? What influence does decaying vegetable matter usu- 

 ally have upon soil? The mass of roots of grass and other 

 plants usually penetrate only twelve or eighteen inches, and 

 in many places this determines the thickness of the loam. 



Which absorbs more heat, a light or a dark color? Illus- 

 trate with many samples, and if possible with an experiment. 



A piece of white and a piece of similar black cloth laid on 

 top of the snow will show this in the winter time. The snow 

 will melt much more rapidly under the black cloth. 



Why are white hats and clothes worn in summer and dark 

 ones in winter? What influence, then, does dark soil have 

 upon the crops planted in it? 



Discuss conditions of soil as to fineness, looseness, soft- 

 ness, etc., and the influence of each upon germination and 

 plant growth. How do we make ground loose and fine? 



