CHILDREN'S GARDENS 15 



3. The value of keeping the back straight as much 

 as possible in doing the work; 



4. Economy of personal strength by using the 

 weight, when possible, instead of the muscles; 



5. The value of doing each part of an operation 

 so as to save labor (or material) in each future stage 

 of the work; 



6. The value of an instant's relaxation at certain 

 points in a series of movements; 



7. The individual speed limit. 



i. To teach the three laws of the lever. 

 PFWPF WP FW 



Fig. A. Fig. B. Fig. C. 



p = power force applied. 



F'= fulcrum point of support. 



W = weight to be lifted or moved. 



Fig. A with fulcrum in the middle, i Ib. power will 

 move i Ib. weight. 



Fig. B with fulcrum four times as far from W as 

 from P, i Ib. power will lift % lb- weight at W. 



Fig. C with fulcrum four times as far from P as 

 from W, i Ib. power at P will lift 4 Ibs. weight at W. 



First let the child lift a spadeful of earth, with the 

 right hand grasping the handle and the left hand 

 grasping the shaft close to the blade. Then let him 

 slide the left hand slowly back close to the right hand. 

 As he does this the spadeful of earth seems to grow 



