trafton] OUTLINE OF NATURE-STUDY 149 



Problems — 



How can we identify the evergreens that grow around here? 

 What use is made of the wood of evergreen trees? 



IV. Winter Sports. 



Roller skating; going around curves, other illustrations of centrifugal 



force. 

 Problems — 



How does roller skating differ from ice skating? 



What other illustrations of centrifugal force can you think of? 



V. Sky Studies. 



The stars and planets; distances, size, relation to earth. 



Observations on constellations, difference between winter and sum- 

 mer, constellations visible at all seasons, how to find the north 

 star. 

 Problems — 



How are stars different from planets? 



Which has the greatest effect on man, the moon, sun, planets, or stars? 



Which the least effect? 



VI. Some Simple Machines that Make Man's Work Easier. 



Pulley, screw, wedge. Common applications of each. Compare lever 



and pulley; inclined planes and wedge. 

 Problems — 



How does each of these machines work so as to enable man to lift 



heavy loads? 

 How many applications of each can you think of? 



VII. How Glass Helps People. 



1. In reading — spectacles. 



2. In seeing afar off — opera and field glasses. 



3. In taking pictures — camera; blueprints; developing, printing. 

 Problems — 



How do glasses help one to see better? 



How do opera glasses seem to bring objects nearer? 



In what ways is the camera like the human eye? 



How can we make blue prints of leaves, or from some negative? 



How many different kinds of cameras are there? 



How are negatives developed? 



What are the different ways of printing? 



VIII. Helps in Being Prompt. 



1 . Watches and clocks. 



2. School electric bells. 



3. Old methods of telling time; sundial, hour glass. 

 Problems — 



We will take an old alarm clock apart to see if we can understand 



how it keeps time. 

 How are our electric school bells arranged so as to give the signals 



for the periods? 



