70 LABORATORY LESSONS IN GENERAL SCIENCE 



two decimal places.) Note how this compares with the 

 value f (1.8). 



3. Note on each scale how many degree-spaces there are 

 between the levels of the mercury when in freezing water, 

 and when in boiling water. Whence comes the f used above ? 

 State how to change readings of centigrade scale into Fahren- 

 heit readings, explaining why 32 is added to the reduction 

 value found. 



4. State how the Fahrenheit readings may be changed 

 into centigrade, and why 32 must now be subtracted 

 before the reduction. 



TEMPERATURE RECORDS 1 



1. Take the temperature readings called for in the blank 

 forms below, and record the same at the time taken. Let 

 these observations be made daily during one week only in 

 each succeeding calendar month throughout the school year. 



1 Lessons requiring the keeping of records where data are to be gained by 

 observation through considerable periods of time must be assigned suffi- 

 ciently long in advance. It is unlikely that too great emphasis will be 

 placed upon the educational value of sustained efforts to accumulate and 

 classify facts. Such facts demand in themselves correct interpretation, 

 and call for keenness of discrimination in relative values. There is cultivated 

 that desirable mental attitude which seeks the truth at every step, and de- 

 mands the facts before passing judgment. However important the facts 

 of such lessons, their manner of acquisition and of use may be of even 

 greater worth educationally. 



