A Seventh Grade Soil Experiment 



C. F. Phipps. 

 The University of Chicago, The School of Education. 



That the work in nature-study and elementary science should 

 be progressive and correlated in the grades, is a fact well ^•ecog- 

 nized by teachers today. In the upper grades of the Elementary 

 School of the University of Chicago, different phases of elemen- 

 tary science are presented, — hygiene in the sixth, electricity in 

 the seventh, and simple scientific phenomena of the home and 

 community life in the eighth. To correlate the science work of 

 the seventh with that of previous grades it has been found well to 

 use the garden work as a basis of transition. If the children have 

 had garden work in the previous years it is instructive to take up 

 a brief experimental study of the' soil, to ascertain approximately 

 what the constituents of the soil are, and its relation to plant 

 growth. 



Let the children bring in samples of school garden soil and 

 weigh very carefully, in an iron pan, a small amount, perhaps 

 100 grams. It is much more interesting if each child can work 

 out his own experiment, but if the class is too large, or the equip- 

 ment insufficient, a demonstration of parts of the experiment by 

 successive groups of two or three, or even by the teacher, will 

 be found profitable. 



First, place the pan of soil on a ringstand and heat very 

 gently to dry out the moisture. If there is time it may be dried 

 by setting aside for a day or two and stirring occasionally. As 

 the soil dries it becomes much lighter in color, and most of the 

 small lumps break up in the process. The stirring may be done 

 with an iron wire or glass rod, preferably the former because of 

 the probability of the glass chipping off as it becomes hot, and 

 adding to the weight of the soil. The amount of water, in grams 

 and cubic centimeters, may be determined by a second weighing. 



To ascertain the amount of organic material consisting of 

 decayed animal and vegetable matter, the soil is next heated very 

 hot, and stirred at intervals of a few minutes. This strong heat 

 should be applied until no further odor can be detected, and no 

 smoke or sparks seen. The soil will probably then be grayish in 

 color, and have the appearance of fine dust mixed with sand and 

 gravel. By another careful weighing the amount of organic mat- 

 ter is obtained. The soil should then be shaken successively 

 through three sieves of different sized meshes, the largest mesh be- 



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