20 GOOD HEALTH 



Each child needs as much as you do, and grown people 

 need more. This shows how much air must come and 

 go every hour to supply the fresh air needed in a room 

 full of school children. 



In almost every city there are old school houses where 

 the rooms do not get fresh air enough; but in New York 

 City the new schoolhouses are made in such a way that 

 each child has eighteen hundred cubic feet of fresh air 

 every hour. 



QUESTIONS 



1. What signs show that the air out of doors is moving? 



2. What experiment shows that warm air rises? 



3. How do you know that your breath is warmer than the air in 

 the room? 



4. How can you find out that the air at the top of a room is 

 warmer than the air near the floor? 



5. Why is there a greater difference between the air of floor and 

 ceiling in winter than in summer? 



6. Describe the experiment with a match at the crack of a door 

 and tell what it proves. 



7. What does the ink experiment show about pure and impure 

 air? 



8. What does breathing do to air in a room? 



9. How big a box would you need to hold one cubic foot of air? 

 10. How many cubic feet of air does each child need? 



