io8 Lessons in Nature Study. 



V. 



Question the class about the uses of water, ice, and snow. 

 Have some of the various poems on snow, winter, etc., read 

 in school. (Lowell's description of winter in the Vision 

 of Sir Launfall is among the finest in literature.) Draw- 

 ing snow crystals is interesting and instructive work. 

 Frost on windows is also very beautiful. An experiment 

 may be made by placing a tumblerful of cracked ice in a 

 warm room. There will soon form on the outside of the 

 glass beautiful frost crystals. This proves the presence of 

 water vapor in the atmosphere. 



LESSONS ON TEETH. 



Among the most interesting things which will be brought 

 in by children will be teeth of animals. Little children 

 sometimes bring their first teeth, and recount the trials 

 they endured in having them extracted. In the country it 

 is easy to obtain teeth from defunct animals, and in the city 

 any dentist will give you a handful if you ask him. 



I. Human Teeth (Pig. 30, i). 



Supply each child with as many as possible. Get pupils 

 to describe a tooth as regards its parts, body, roots, and 

 crown. The enamel and the dentine, with the small masses 

 of cement adhering to the ends of the root, are all easily 

 seen and described. If you find among the teeth one 

 which has been decayed, you can show to the pupils the 

 pulp-cavity inside. Differences between single and double 

 teeth should be brought out. 



Tell the children to feel their teeth, and see where single 

 and double are. Tell them to count their teeth. If any 

 one brings in a " milk-tooth," show it to the children, and 

 let them see that it has no root, etc. 



I have found it very interesting " seat-work " to pass 

 around a large handful of human teeth, and get the chil- 



