Bausch & Lomb School Microscopes Special Prices Quoted to Schools BH 4 Microscope, $29.50 A most practical low priced instrument for secondary and high school use. The new construction of arm with hand hold and fine adjustment makes it especially durable for inexperienced pupils to use. This microscope has coarse and fine adjustments, 2 eye pieces. 2-3 and 1-6 objectives, double nose piece and iris diaphragm in stage. These two Microscopes should AH 1 outfit has sliding tube coarse adjustment, hand hold arm with fine adjustment, one eye piece. 2-3 and 1-6 objectives, large. double mirror and large stage. interest every teacher. They have so many new features that cannot be told of Bausch & Lomb Optical Co. Rochester, N. Y. New York Boston Washington Chicago San Francisco Frankfurt a/M Germany We Ask Our Readers To Notice The Advertising Columns CONTENTS FOR MARCH, 1907. PROFIT AND LOSS IN EXPERIMENTAL CHEMISTRY-Lyman C. SOME MODERN NOTIONS IN THE RATIONAL TEACHING OF ELE- SUGGESTIONS FROM BACTERIOLOGY AND SANITATION FOR 165 176 183 196 204 210 SPIDER STUDY IN A ZOOLOGY COURSE—Wilbur H. Wright 215 219 221 224 229 233 RESUME OF CURRENT MAGAZINES FOR TEACHERS OF SECON- The American Federation of the Teachers of the Mathematical and THE HORATO SCHOOL SCIENCE AND MATHEMATICS VOL. VII. No. 3 CHICAGO, MARCH, 1907 WHOLE NO. 50 PROFIT AND LOSS IN EXPERIMENTAL CHEMISTRY.* BY LYMAN C. NEWELL, PH.D., Professor of Chemistry, Boston University. The teaching of experimental science involves grave difficulties. It is my purpose in this paper to point out some of the difficulties presented by experimental chemistry and to suggest means for their elimination. The profit and loss arising from a course in chemistry is by no means limited to the experimental part. Numerous pedagogical difficulties exist in all branches of this science. But it seems prudent to limit the present discussion to the experimental content. The delimitation is made partly from insufficient time to consider the whole field but mainly from a conviction that the problems arising out of the laboratory work are more closely connected with the profit and loss account of teachers and students. I. The best method of teaching chemistry is undoubtedly the one that includes all avenues of approaching the student's mind-demonstration lecture, informal conference, frequent recitation, text-book study, written and oral tests, varied experiments, and so on. These pathways, however, are not equally productive. Demonstration lectures please a majority, informal conferences and recitations help a minority, while examinations irritate a plurality. Text-books are complacently studied and believed, but in themselves they yield uncertain results. Real mental work begins when the student enters the laboratory and tries to correlatė the concrete facts gleaned in his work-shop with the abstract. data read in his study or gathered by his experimentations. And 1906. Read before the Central Association of Science and Mathematics Teachers, Nov. 03. unless he is provided with proper experimental work and conducted judiciously through it, particularly during its early stages, he loses the mental training which such work is designed to provide. Consider the mental equipment of most students who begin chemistry. The study of history and language has occasioned much memorizing and led to a potential store of disconnected facts largely outside the student's daily life and experiences. The mathematics, too often shirked or perfunctorily performed, has exercised the critical faculties but has involved little or no contact with concrete data. The science if studied at all is apt to be so distorted, incomplete, and unrelated that it is positively pernicious in advanced work. My color scheme may be too somber but you may decide for yourselves as to the general correctness of the picture. Consequently when the student begins chemistry he enters a new world. It is unfamiliar and transcends his experience. He is appalled by the language, the apparatus, and the manual operations. He is likewise distracted by facts, things, and unyielding results. He soon discovers, too, that his work is no longer abstract. Day after day he is summoned before the bar of concrete tasks and commanded to observe things, to tell what he sees, and to interpret their meaning. But in his previous work he seldom made accurate observations and he infrequently drew logical deductions. So the first days in the laboratory are irksome, fruitless, or absurd to student and teacher alike. And this inability to observe, think, and conclude with reasonable accuracy may continue indefinitely if not corrected as far as possible at the beginning of the course. Too often the beginner is pushed into a mysterious labyrinth and expected to escape by the time the bell rings for the next period. He may emerge but he cannot tell the method of escape or repeat the adventure. The error in the early days of laboratory instruction is the failure to construct a bridge between the past experience and the new experience. Connections between the known and the unknown must be built quickly. No subject can be learned unless it is connected with other subjects. And the more numerous and obvious the connections are, the more quickly will the new subject be grasped. The beginner in his new world is not blind but awestruck, not stupid but bewildered, not dumb but uninformed. Therefore the keynote of the early laboratory work |