Febkuakt 22, 1918] 



SCIENCE 



183 



bars, boats, automobiles, telephones; it is wise 

 to start out with this knowledge and unify it; 

 he knows he must solve problems in practise, 

 with pulleys, hydraulic rams, cameras or wire- 

 less instruments; he should see that his phys- 

 ics is leading to an ability to do these things. 



In mass teaching, such as teaching in most 

 American institutions must be, the aim of the 

 teacher must be at the average man in the 

 class. The ground covered, the rate at which 

 it is covered, and its relative difficulty, must 

 depend on the ambitions of this average man; 

 these can be determined only by " feeling of " 

 the class, and change from year to year. 

 While this matter is one too extensive for 

 treatment here, it should be noted that the 

 problem is by no means a simple one; the 

 teacher is only one element in the competition 

 of which the student is the center, and he and 

 his course can not always hope to master the 

 student's attention against the intense pres- 

 sure of fraternities, games, " Wein, Weiber 

 und Gesang." To play a part in this competi- 

 tion and win any real success implies that the 

 teacher must realize the situation and be ready 

 himself to exert a sensible pressure. The easy- 

 going notion that they may take it or leave it — 

 that's their business— is as much out of plac« 

 in the teaching of physics as it is in the selling 

 of hair-wash and automobiles. I believe that 

 college administrations are more at fault in 

 their iU appreciation of this than are college 

 teachers, though something can be said on both 

 sides. 



The teaching methods usually adopted for 

 elementary work are lectures, text-book study 

 with problem-solving, and laboratory work. 

 Each has its peculiarities, its limitations and 

 difficulties. 



Physics lectures are carried on with experi- 

 ments, qualitative or semi-quantitative, which 

 the audience observes under the guidance of 

 the speaker, without ha^ang to supply skill or 

 initiative. This method is the only one for 

 the exposition of original research or recent 

 progress ; many experiments are valuable when 

 taken up thus and less so otherwise; the more 

 or less passive attitude of the audience is the 

 great weakness. It does very well as an easy 



way for beginning or general classes; pedagog- 

 ical tricks, like written notes and quizzes, help 

 to diminish somewhat the somnolence due to 

 passivity. However, every lecture is probably 

 more valuable to the speaker than to any of his 

 hearers. Every teacher who uses this method, 

 and requires the completion of written note- 

 books on the course, should read some of these 

 notebooks with some care. He will learn 

 something about the value to the audience of 

 his own lectures. 



The presentation of lecture experiments is 

 often weakened by inattention to the details of 

 lighting. An experiment which only a few of 

 the audience can see is wasted, however it may 

 please the lecturer, for it is his business to 

 " get it over " just as much as if there were 

 footlights between him and his hearers. It is 

 not enough to set the apparatus up — it must 

 go; and it is not enough that the experiment 

 go — the audience must see it; and weak light- 

 ing of the critical point, glitter and glare on 

 glass surfaces, supports in the way, etc., some- 

 times hinder the audience from seeing. While 

 the experiment is being tried out in advance 

 the lecturer should view it from the audience 

 space and from the most disadvantageous 

 points, to correct such weaknesses. 



The combined recitation and laboratory 

 method makes greater demands on Uie mem- 

 bers of a class than the lecture method. I do 

 not believe that any student should be allowed 

 to take a purely text-book course in elementary 

 physics; the laboratory should invariably ac- 

 company the recitation. 



The study of a book, the solution of prob- 

 lems, the answering of questions, give play to 

 both originality and skill; book explanations 

 and descriptions of experiments not only 

 lead to an understanding of work performed in 

 the laboratory, but they bring in order before 

 the mind the results of experiments and ob- 

 servations which only a favored few can ever 

 directly know because of difficulty, expense or 

 length of time required. 



The objects of laboratory work are two; to 

 illustrate (not demonstrate) the laws of nature, 

 and to teach the technique of experiment. 

 This latter is apparently only secondary, but 



