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Preparation of entering students à

factor

SOM

V.

THE TEACHING OF CHEMISTRY

OME of the students entering classes in chemistry in college have already had an elementary course in the determining subject in the high school or academy, while others have not. Again, some study chemistry in college merely for the sake of general information and culture, while many others pursue the subject because the vocation they are planning to make their life's work requires a more or less extensive knowledge of chemistry. Thus, all students in the natural sciences and their applications as we have them in medicine, engineering, agriculture, and home economics as well as those who are training to become professional chemists, either in the arts and industries or in teaching, must devote a considerable amount of time and energy to the study of chemistry. The teacher of college chemistry consequently must take into consideration the preparation with which the student enters his classes and also the end which is to be attained by the pursuit of the subject in the case of the various groups of students mentioned.

In the larger high schools courses in chemistry are now quite generally offered, but this is not yet true of the smaller schools. In some colleges those who have had high school chemistry are at once placed into advanced work without taking the usual basal course in general chemistry which is so arranged that students can enter it who have had no previous knowledge of the subject. In other words, in some cases the college builds directly upon the high school course in chemistry. As a rule, however, this does not prove very successful, for the high school course in chemistry is not primarily designed as a course upon which advanced college chemistry can be founded. This is as it should be, for after all, while the high school prepares students for college, its chief purpose is to act as a finishing school for those larger numbers of students who never go to college. The

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high school course in chemistry is consequently properly designed to give certain important chemical facts and point out their more immediate applications in the ordinary walks of life, as far as this can properly be done in the allotted time with a student of high school age and maturity. The result is consequently that while such work can very well be accepted toward satisfying college entrance requirements, it is only rarely sufficient as a basis for advanced college courses in the subject. As a rule it is best to ask all students to take the basal course in general chemistry offered in college, arranging somewhat more advanced experiments in the laboratory wherever necessary for those who have had chemistry in preparatory schools. This has become the writer's practice after careful trial of other expedients. The scheme has on the whole worked out fairly well, for it is sufficiently elastic to meet the needs of the individual students, who naturally come with preparation that is quite varied. Almost invariably students who, on account of their course in high school chemistry, are excused from the general basal course in college chemistry have been handicapped forever afterward in their advanced work in the subject.

of first-year course

General

chemistry

The first year's work in college chemistry consists of Organization general chemistry. It is basal for all work that is to follow, and yet at the same time it is a finished course, giving a well-rounded survey of the subject to all who do not care to pursue it further. This basal course is commonly given in the freshman year, though sometimes it is deferred to the sophomore year. Its content is now fairly uniform in different colleges, the first semester being commonly devoted to general fundamental considerations and the chemistry of the non-metals, while the metals receive attention in the second semester, the elements of qualitative analysis being in some cases taught in connection with the chemistry of the metals.

The work is almost universally conducted by means of lectures, laboratory work, and recitations. The lectures have the purpose to unfold the subject, give general orienta

tion as to the most important fundamental topics and points of view, and furnish impetus, guidance, and inspiration for laboratory study and-reading. To this end the lectures should be illustrated by means of carefully chosen and well-prepared experiments. These serve nat only to illustrate typical chemical processes, and fundamental laws, but they also stimulate interest and teach the student many valuable points of manipulation, for it is well-nigh impossible to watch an expert manipulator without absorbing valuable hints on the building up, arranging, and handling of apparatus. In the lectures the material should be presented slowly, carefully, and clearly, so that it may readily be followed by the student. Facts should always be placed in the foreground, and they should be made the basis of the generalization we call laws, and then the latter naturally lead to theoretical conceptions. It is a great mistake to begin with the atomic theory practi cally the first day and try to bolster up that theory with facts later on as concrete cases of chemical action are studied. On the other hand, it is also quite unwise to defer the introduction of theoretical conceptions too long, for the atomic theory is a great aid in making rapid progress in the study of chemistry. At least two or three weeks are well spent in studying fundamental chemical reactions as facts quite independent of any theories whatsoever, in order that the student may thoroughly appreciate the nature of chemical change and become familiar with enough characteristic and typical cases of chemical action so that the general laws of chemical combination by weight and by volume may be logically deduced and the atomic and molecular theories presented as based upon those laws.

Up to this stage the reactions should be written out in words and all formulation should be avoided, so that the student will not get the idea that "chemistry is the science of signs and symbols," or that "chemistry is a hypothetical science," but that he will feel that chemistry deals with certain very definite, characteristic, and fundamental changes of matter in which new substances are formed,

and that these processes always go on in accordance with fixed and invariable laws, though they are influenced by conditions of temperature, pressure, light, electricity, and the presence of other substances in larger or smaller amounts. The theory and formulation when properly introduced should be an aid to the student, leading him to see that the expression of chemical facts is simplified thereby. Thus he will never make the error of regarding the symbol as the fundamental thing, but he will from the very outset look upon it simply as a useful form of shorthand expression, as it were, which is also a great aid in chemical thinking. Facts and theories should ever be kept distinct and separate in the student's mind, if he is to make real progress in the science.

A thoroughgoing, logical presentation of the subject, leading the student slowly and with a sense of perfect comprehension into the deeper and more difficult phases, should constitute one of the prime features of the work of the first year. Interest should constantly be stimulated by references to the historical development of the subject, to the practical applications in the arts and industries, to sanitation and the treatment of disease, to the providing of proper food, clothing, fuel, and shelter, to the problems of transportation and communication, to the chemical changes that are constantly going on in the atmosphere, the waters, and the crust of the earth as well as in all living beings. Nevertheless, all the time the science should be taught as the backbone of the entire course. The allusions to history and the manifold applications to daily life are indeed very important, but they must never obscure the science itself, for only thus can a thorough comprehension of chemistry be imparted and the benefits of the mental drill and culture be vouchsafed to the student.

For the freshman and sophomore, two lectures per week are sufficient for this type of instruction. In these exercises the student should give his undivided attention to what is presented by the lecturer. The taking of notes is to be discouraged rather than encouraged, for it results in divid

Methods of The Lecture method

teaching

The

laboratory work

ing the attention between what is presented and the mechanical work of writing. To take the place of the usual lecture notes, students of this grade had better be provided with a suitable text, definite chapters in which are assigned for reading in connection with each lecture. The text thus serves for purposes of review, and also as a means for inculcating additional details which cannot to advantage be presented in a lecture, but are best studied at home by perusing a book, the contents of which have been illuminated by the experimental demonstrations, the explanations on the blackboard, the charts, lantern slides, and above all the living development and presentation of the subject by the lecturer. The lectures should in no case be conducted primarily as an exercise in dictation and note taking. If the lectures do not give general orientation, illumination, and inspiration for further study in laboratory and library, they are an absolute failure and had better be omitted entirely. On the other hand, when properly conducted the lectures are the very life of the

course.

The laboratory work should be well correlated with the lectures, especially during the first year. The experiments to be performed by the student should be carefully chosen and should not be a mere repetition of the lecture demonstrations. The laboratory laboratory experiments should be both qualitative and quantitative in character. They should on the one hand illustrate the peculiar properties of the substances studied and the typical concomitant changes of chemical action, but on the other hand a sufficient number of quantitative exercises in the laboratory should be introduced to bring home to the student the laws of combining weights and volumes, thus giving him the idea that chemistry is exact and that quantitative relations always obtain when chemical action takes place. At the same time the quantitative exercises lay the basis for the proper comprehension of the laws of combining weights and volumes and the atomic and molecular theories. At least three periods of two consecutive hours each should

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