TEACHING INORGANIC CHEMISTRY TO THOUSANDS*
About two years ago an article appeared in THISJOURNAL% describing the remarkable growth of the chemistry department of Washington Square College. At present the annual enrolment in beginning chemistry is almost 1400. This is a larger number than the total annual enrolment (all courses) of 70y0of our accredited American universities and colleges. Table I, compiled by the writer from data found in "American Universities and CoIlege~,"~ will give an idea of. the general distribution of students in our institutions of higher learning. All the colleges and universities on the accredited list of the American Council of Education (1927) were included in making the table. They number 384. The table is reproduced simply for the convenience of those who may wish to make comparisons similar to the one above. I TABLE Total annual enrolment
Less than 500 Less than 750 Less than 1000 Less than 1400 Less than 2000 Less than 2500
percentage of total number of colleges and "niversitie~
Total annual enrolment
Up to 500
35 54 60 70 78 82
500-750 750-1000 1000-1400 1400-2000 '2000-2500
Over2500
Percentage of total number of callegea and universities
35 19 6 10 8 4 18
The main purpose of this article is to describe (1) the organization of the teaching unit, and (2) the methods used in imparting annually to such a large number of students a goodly portion of the body of facts and theories called inorganic chemistry. We shall give the first matter but scant attention since the organization of the teaching unit is of minor importance and its size will vary from college t o college.
The Teaching Unit We have nine lecturers, including one associate professor, four assistant professors, and four instructors. The student listens to two or three lectures per week depending upon whether or not he has been "exposed" to chemistry in secondary school. The lectures are supplemented by adequate demonstrations, lantern slides, and motion pictures. Attendance
* Presented before the Division of Chemical Education of the A. C. S. at Minneapalis, Minnesota, September 10, 1929. 1 MacTavish, Wm. C., THIS JOURNAL, 5,455-6 (Apr., 1928). Wobertson, "American Universities and Colleges," Charles Scribner's Sons, New York City, 1928. 321
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a t the showing of the latter is voluntary. During the coming year i t is proposed to further supplement the lectures by conducting monthly trips to industrial plants. The size of the lecture sections varies considerably due to limitations of space and time. Three sections number approximately 2.50 students; five sections have approximately 100; three or four sections have approximately 50 students. The laboratory instruction, quiz, and recitation work is carried on mainly by thirty graduate assistants although the instructors and professors are also assigned to laboratory and quiz duties. Each laboratory of sixty students has a teaching personnel of three; one experienced graduate assistant or instructor and two graduate assistants, usually less experienced. The students are apportioned among the three assistants. The quiz and recitation hour, comprising thirty students to the class, is presided over by one of the professors, an instructor, or by an experienced graduate assistant. Method of Teaching So much for the teachers, now for the teaching. The lecturers follow a standard textbook rather closely. This is necessary since the examinations which come each quarter-semester are the same for all students enrolled in the course. Needless to say the cooperation of all the lecturers is required in setting the questions for these examinations. In order to conrdinate the work in th? lahoratory and quiz sections with the lectures a schedule is posted each semester which gives the date and subject of each lecture, the experimental kork to he performed each week in the laboratory and the work to be undertaken each week in the quiz sections. Besides this, one of the lecturers acts as overseer of the lahoratories and quiz sections thus helping to keep them all coordinated and functioning in an efficient way. In this college we consider the laboratory as a most important if not the most important adjunct in the teaching of inorganic chemistry. I t is here that the instructor and the student come in close contact and it is here that the most effective teaching can be done. In order to insure the latter, a weekly assistants' meeting is held a t which plans are laid for the conduct of the laboratories during the following week. This brings harmony into the group and makes for uniformity in the facts to he presented, methods of presentation, and experiments to he performed. In our laboratory instruction we have established several rules which we believe are fundamental to success. They are: 1. All the assigned work i s to be done independently by each student. If an experiment requires working together in pairs or larger groups i t is best to omit it or have it carried out in the form of a demonstration by the instructor or assistant in charge of the laboratory.
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2. A s much of the manual work i s to be performed by the student as 90ssible. This is to insure the proper coordination of mind and hand and the acquisition of the dexterity so necessary to our future chemists, physicists, physicians, and dentists. The assistants are requested to do as little lecturing or demonstrating as is compatible with the smooth running of the class as a whole. 3. Instruction i s to be mostly of the man to man or canvassing type. The laboratory instructor passes from student to student, spends five or ten minutes with each one, asks questions and corrects errors in statements, notes, or apparatus. This individual instruction and questioning is most important and when properly carried out is not only an effectiveteaching tool but helps to obtain a reliable estimate of the student's knowledge and ability. 4. The student i s to keep notes and answer questions as directed in the laboratory exercises. At the end of each laboratory session the assistant receives the notes and goes over them carefully, underscoring the errors. These notes are returned to the students a t the beginning of the next laboratory session. The quiz or recitation hour is one which, in the opinion of the writer, should form a part of every inorganic chemistry course. During this hour the student can let his light shine forth. Here, in a small responsive section, he can ask questions, think out loud, voice opinions, engage in re9arteeall of course if the instructor has the class well in hand and controls as well as encourages this active type of recitation. The pro#' cedure followed in our quiz section is: 1. A written quiz for ten-fifteen minutes starts the hour. This kills two birds with one stone. It places a penalty on tardiness and gives an additional weekly grade with minimum loss of time. The instructor grades these quizzes and returns them to the student a t the next meeting. 2. The remainder of the hour is given over to a n informal quizzing and discussion of the problems and questions assigned by the weekly schedule. The reader may sit back, wonder, and finally ask the perfectly natural question, "This all seems very well on paper, but how can you be sure i t is working in practice?" The answer is, firstly, by proper oversight and, secondly, by requiring that the laboratory and quiz instructors and assistants turn in fortnightly reports of the grades and progress of each student under their care. Each instructor has a report blank for each class, the blank being large enough to accommodate all the grades for one semester. This not only serves as an effective check on assistants but i t gives the instructor an excellent means of estimating the final grades of his students. Another natural question would be, "Is this system as successful in small colleges as in large?" The author knows of two smaller colleges where
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it has been tried and found quite satisfactory. In fact the smaller the college the easier i t becomes to insist on individual work on the part of the student and individual instructio?~on the part of the assistant. In concluding, the writer wishes to thank his colleagues a t New York University and other institutions for their valuable suggestions and contributions toward making this particular system of teaching freshman chemistry a success.
Pioneer of Wave Mechanics Is Nobel Prizeman in Physics. One of the modern Alices in the wonderland of the newer physics, Duc de Braglie, scientific scion of a proud French family and member of the French Academy by scientific right as he is royalist by inheritance, is wearer of the Nobel laurels for physics for 1929. In this high award, physicists see a compliment to a new way of looking a t the phenomena of light, electricity, and other stuff of which the universe is made. For Duc de Broglie was the pioneer in the development of that most modern branch of physics, "wave mechanics," which the German physicist, Schroedinger, developed to an even greater extent. The theory of wave mechanics as propounded by de Broglie and Schroedinger makes the differences between matter and radiation a shadowy borderland. An electron, the unit of electricity and the smallest particle of matter, becomes a sort of manifestation of a group of waves, while waves of light or other radiation a t times take on the -properties of particles. And then a t other times matter is best explained as acting like waves of radiation. All this is disconcerting to those who!earned about light, X-rays, and other radiations some years ago when they were considered wave motions. Despite the new wave mechanics, the classical wave theory of radiatmn accounts for ordinary optical phenomena with satisfaction and for practical purposes it is not thrown overboard. Yet wave mechanics explains some mysteries unsolved by earlier conceptions and therefore the physicist is in the position of having more than one fundamental law. He uses the one that fits best, confident in the hope that future progress will destroy their apparent inconsistencies. One daring prediction made by Duc de Broglie when he first developed his wave mechanics a few years ago was fulfilled by the discovery of the American physicists, C. J. Davisson and L. H. Germer, that electrons, particles of matter, act like waves in the same sense that light and X-rays are vaves.-Science Service Acids from Burning Coal Make Exposed Copper Green. The green patina that appears on copper roofs or drain pipes after years of service and that gives the metal its attractive appearance is due chie0y to sulfuric acid present in the air from coal smoke. This conclusion was announced at the meeting a t Duesseldorf, Germany, of the Institute of Metals, an English society holding its first meeting in Germany, by Dr. W. R. J. Vernon and L. Whitby of the Chemical Research Laboratory a t Teddington. The two metallurgists studied samples of copper from buildings in London and other parts of England. Some were as old as three hundred years. I n the city specimens, the patina consisted of basic copper sulfate, caused by the action of atmospheric sulfuric acid. A piece of telegraph wire, exposed for 13 years within 200 yards of the sea, showed a patina consisting of basic copper chloride, the chlorine having been furnished from the salt water. At first, they found, the red copper turns black, but then the green patina develops later, and remains indefinitely.-Science Service ~
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