IV 



ELEMENTS OF GENERAL SCIENCE 



There is a science of science teaching. This new science is 

 young. It is not recognized as yet by many who profess them- 

 selves to be hospitable to every form of research. But the new 

 science can afford to be patient. The greatest conquests of which 

 the older sciences are so proud are all matters of a century, at 

 most, and many of these conquests fall within the memory of our 

 own generation. There are men now working in biology who 

 remember well the beginnings of the modern period in that 

 science. So it will be with the science of teaching. Once we 

 realize the value of experimentation, once we take seriously the 

 problem of adapting intellectual material to real needs, we may 

 look for a rapid and satisfactory growth in this our new science. 



The unity of this introductory course in science is secured 

 by use of the logical interrelations between the topics which 

 compose the course. No attempt is made to maintain the 

 unity of any one of the different sciences. Experience shows 

 that after use of this course pupils do not feel that they 

 " have had " any of the differentiated sciences, as physiog- 

 raphy, physics, chemistry, or biology. They are, however, 

 much interested in the later study of the differentiated 

 sciences. The topics of the course are readily grouped under 

 six major divisions. Within these major divisions the topics 

 are arranged so that there is coherence and progression in 

 the work. The authors have selected the materials and have 

 organized the course upon the ground of pedagogical value, 

 as shown by classroom experiment. 



The new edition has been almost entirely rewritten. The 

 organization and method of the first edition are satisfactory 

 in practice and are retained. Because of added scientific dis- 

 coveries and educational experimentation it has been found 

 desirable to add new material throughout. A few minor 

 topics have been omitted. To the third major division, Work 

 and Energy, chapters have been added upon the important 

 topic Electricity. Following the discussion of the source of 

 the energy used on the earth and preceding the division The 



