136 Education through Nature 



V. EXPERIMENTS. 



The Fifth Step may often be omitted when the 

 subject under consideration does not especially favor 

 a physiological or physical treatment. Yet it is an 

 important step and should not be neglected when 

 the problems of the subject require it. 



The first thing to be done in performing an experi- 

 ment is to state the problem. This may be done 

 by the teacher; but better still, the pupil may be led 

 to state it after he has been made to realize that a 

 problem actually exists. The second important ele- 

 ment to consider is what factors must be present and 

 what ones excluded from the experiment. 



The simpler the experiment and the less elaborate 

 the apparatus the more effective usually is the result. 



SOME SIMPLE EXPERIMENTS. 



I. On Solutions, (a) Compare salt or sugar with 

 starch. What difference in appearance? (&) Fill 

 two tumblers half full of water; put into one a tea- 

 spoonful of salt or sugar; stir. The salt or sugar dis- 

 appears. What has happened? (c) Put a spoonful 

 of starch into the second tumbler. It does not dis- 

 appear. Why not ? What would happen if the starch 

 could be changed into sugar? 



II. On the Reaction o) Starch, (a) Put some flour 

 into a small quantity of boiling water; treat the paste 

 with a few drops of iodine solution (iodine dissolved 

 in 30% alcohol); it turns blue. (6) Treat a small 

 piece of boiled potato in the same way. Any evidence 

 of starch ? (c) Put a green leaf into boiling water and 

 treat it with iodine. Any evidence of starch in the 

 leaf? 



III. On Diffusion, (a) Put some sugar into a tum- 

 bler, and pour into it enough water to fill the tumbler. 

 Allow it to stand. Does the sugar disappear? (b) 



