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SCIENCE 



[N. S. Vol. XXVIII. No. 724 



struction, and to our graduates at the close 

 of their period of study at the institute. 



It is true that a part of the power of a 

 scientific man depends upon his knowl- 

 edge ; and a part of our task as teachers 

 consists in bringing him into permanent 

 possession of those kinds of knowledge 

 which are most essential. In connection 

 with this work of imparting knowledge I 

 ask you to note three kinds of errors into 

 which we are especially apt to fall. 



First, it is a common mistake to ply the 

 student with more than he can possibly 

 assimilate. For covering a certain subject 

 we are allowed a limited number of hours ; 

 into that time we feel that we must crowd, 

 at any rate, all the obviously important 

 topics. This we make the consideration of 

 prime importance, whereas we should first 

 determine what principles and essential 

 facts can, in the amount of time given, be 

 treated with sufficient thoroughness to 

 enable the student really to comprehend 

 them and make them his o^vn. We must, 

 therefore, constantly examine the courses 

 that we are giving, to see whether they are 

 not overcrowded; and, if they are over- 

 crowded, we must consider how they may 

 be disencumbered, so that the main points 

 may be properly emphasized. Obiter dicta 

 have no place in a course of instruction: 

 principles which there is not time to drive 

 home should not be mentioned at all; for 

 they simply confuse the student, by dis- 

 tributing his attention over a larger num- 

 ber of topics than he can possibly assimi- 

 late at one time. 



The existing conditions make the com- 

 mission of this error only too easy. There 

 is a constant demand that we give our 

 students a wide variety of information. 

 Not to teach a phase of a subject which 

 may be regarded as important invites criti- 

 cism and argues incapacity on the part of 

 the teacher. Moreover, in many subjects 

 we are badly off in the matter of text- 



books : most of our so-called text-books are 

 really treatises and reference books. 

 "Would that some competent person would 

 write for a ninety-hour course in chemistry 

 or physics a text-book containing only 

 those facts and principles that can be 

 properly taught in a ninety-hour course! 

 It is this defect which has led so many of 

 the institute professors to prepare notes of 

 their own, the object of which is primarily 

 to emphasize the more fundamental prin- 

 ciples of the subject. 



Notwithstanding these difficulties, how- 

 ever, it is our clear duty as teachers con- 

 stantly to endeavor not so much to teach 

 many things as to teach well— not so much 

 to "cover the ground " ourselves, as to 

 make sure that our students go over the 

 course with us. In trying to include too 

 much, we not only sacrifice the opportunity 

 for training, of which I shall speak later, 

 but we accomplish far less than we might 

 even in the matter of imparting knowledge. 



The second error of which I would speak 

 is the failure to keep sufficiently in touch 

 with the mind of the student— to appre- 

 ciate the knowledge which he actually 

 possesses and the degree of development of 

 his mental powers. The unfortunate re- 

 sults of this error are most clearly and fre- 

 quently observed in lecture courses. The 

 lecturer is apt to look at his task merely 

 from an objective view-point: if he pre- 

 sents his subject clearly and logically, he 

 complacently feels that he has done his 

 part, and that it is the fault of the student 

 if he has failed to profit by it. Yet the 

 real test of the success of a lecture course, 

 as of any other form of instruction, is the 

 amount of benefit that the student actually 

 derives from it ; and the teacher must fre- 

 quently, by some means or other, apply 

 this test, must consider the causes of his 

 incomplete success, and introduce such 

 modifications as seem likely to lead to 

 better results. He must keep in touch 



