TWENTY YEARS OF EXPERIMENTING IN TEACHING COLLEGE CHEMISTRY* OR M~ssounr,COLUMBIA, MISSOURI H B R ~ ASN C ~ U N DUNIVERSITY T, For twenty years our introductory college course in chemistry has embraced classroom work (lectures, recitations, quizzes, demonstration experiments) and laboratory work by students. A standard college textbook and a laboratory manual have always been required. The manual now used requires no notebook for laboratory record. Experimental data are recorded on blank pages of the manual: and answers to questions in the mannal are recorded in the space provided. A notebook, however, is kept by the student for filing classroom exercises. Notes on lectures are not required, but students mark passages in the text as the lecture proceeds. The course has always been on a five-hour basis, with three lectures per week and twolaboratory periods of two hours each. -Thefull course extends over two semesters, the total credit being ten hours. For ten or perhaps twelve years, an additional conference period has been required, bringing the total hours of attendance by the student in classroom and laboratory up to eight hours per week. The assignments for homework probably require about six hours per week of work outside the classroom, making a total of about fifteen hours per week of student application. The additional conference period was the result of a request by students following an experiment with a small group in the summer session. The conference groups are small-twelve to eighteen students, and are conducted by the students' laboratory instructors. It is a period for study and drill in working problems. Each laboravry instructor attends one of the class lectures, and thus coordination between class and conference work is maintained. Laboratory Work Laboratory work is conducted in small laboratories, fifteen to eighteen students in each section, supervised by one instructor. Individual laboratory work is the rule. Each student is supplied with locker and individual equipment, but has no reagent bottles on his table. One side shelf for reagents, centrally located, suffices for each room. Quantitative experiments are emphasized, and are required to be performed in duplicate: i. e., a first and a second trial. Several unknowns are introduced: for example, under specific heat, the student is given a metal bar of unknown composition; the percentage of water in an unknown hydrate is assigned; in neutralization, the normality of a base and acid is determined. Each student in a section is furnished a different sample. This feature of laboratory work, it seems to me, can be extended even to the experiments of the first semester. It has been given more prominence in our work within the past three years. * Presented at the meeting of University of Missouri Section of A. C. S. devoted to the Teaching of College Chemistry. December 6. 1929. 1310
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Filling out answers to questions and problems in the laboratory manual involving ideas closely related to the experiment, has distinct advantages. The student always brings the textbook to laboratory and refers to i t frequently, thus securing better coordination between the two phases of work. Incidentally the student is compelled to study the text. No time is spent in copying directions from laboratory manual into notebook. The time usually so spent by the student is put in looking up answers to questions. All laboratory notes are made by the student during the laboratory period, and these notes are made in duplicatecarbon copy being given the instructor for correction and record. This is the second semester we are experimenting with this system of laboratory notes. Our laboratory instructors find that the lack of skill in arithmetic has retarded laboratory experiments materially. To remedy tliis, in part, we spent about two weeks a t the beginning of the term in reviewing arithmetic, under the head of the metric system, but including the computation of large and small numbers, decimals, positive and negative exponents, etc. Classroom Work As I look back to my early program for lectures, i t seems to me that the greatest transformation in the character of the instruction has taken place in this phase of the course method. The transition has been gradual, and each new year sees a series of changes. We have not even now evolved a standard system although the high points in the course remain unchanged. Our lecture classes have ranged in numbers from thirty-five to one hundred seventy-five. With the larger sections, several instructors are present. They help the students in the written work, which has now become a daily part of the classroom period. Having served for a time during my early years as lecture assistant in general chemistry, I had a fondness for lecture demonstrations as a means of arousing interest, and as the best method of imparting knowledge of chemical phenomena. I had also camed away with me the many vivid scenes from the attendance a t a course of lectures in general chemistry given by an eminent German professor, whose hobby evidently was elegant lecture demonstrations. This veteran performer, assisted by well-trained helpers, now and then said that the ideas we get by reading may soon be forgotten, but those things which are seen will always be remembered. My experience, however, has convinced me that ideas gained through visual methods fade away very readily from freshmen. During the early years of this teaching experiment we probably introduced too great a variety of experiments. There is a real danger here of bewildering the student. In the first place, he will not differentiate between such demonstrations as are basic, and those that are mere pleasing incidents. Again, the experiment, without full discussion, may get but little beyond the stu-
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dent noting a smoke, an explosion, a stink. Gradually, as the years have passed, we have reduced the number of lecture experiments, centered our attention on the more basic demonstrations, and elaborated the experimental equipment by not infrequently repeating the experiment with modified apparatus. For example, the decomposition of water by electrolysis is repeated at least four times with four different types of apparatus, but each piece of apparatus is brought to the attention of the class at different stages in the course. A student or two always assist me with certain parts of the experiment and with the equations for the reactions demonstrated. The burden of any necessary blackboard writing is always delegated to a student. This method takes more time, but the compensationis a higher index of attention by the class. Exhibits are for the most part materials or app&atus which are being used in the demonstrations. Of course, we all have experiments go wrong, but this must be a rare occurrence, indeed, for experimental "set ups" which show the principle but fail to function properly, are now considered jokes by students. Demonstrations in order to be effective must be carried out with skill, and the experiment must work. Demonstrations follow assigned readings as a rule. In our early years we lectured and demonstrated profusely, day after day, assigned readings and problems for homework, and then after a month announced a written quiz, for which the student crammed diligently. Only the conscientious, independent workers of the assigned problems maintained any sustained daily preparation. Now we have daily recitat~ns,and by sustained repetition manage to force the class average on a one-hour written quiz up to 60 and even 65, which is not so bad considering the fact that the graders (in this case, graduate assistants and instructors) scale down severely for mistakes. Repetition has become the watchword of our efforts in class instruction. The number of topics now included looks greatly reduced in comparison with our earlier attempts, but far more emphasis is being placed on the topics studied. The present course is a far more intensive course, intensified by repetition of basic ideas. At the very outset, the law of multiple proportions and the law of combining weights have been set aside. The chemical equation, with all the wonderful array of facts it shows when it finally receives the touchstone of the molecular theory, is made the 6rst cornerstone in our program. Then comes the idea of concentration-in terms of moles; and following this the relation between electricity and chemical change--the close relation between electricity and matter including valence, which culminates through the discoveries in radioactivity in the structure of the atom. This sequence is unfolded in connection with a study of a few typical elements and compounds: oxygen, hydrogen, water, hydrogen chloride, sodium hydroxide, chlorine, sulfur, the alkali and alkaline earth metals.
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Daily Written Tests and Monthly Quizzes
A glance a t one of the class record books for this semester shows that we have already recorded about forty grades for each student. Three onehour quiz grades are also recorded. We are able to keep these records by having an adequate force of problem readers. Each day ten to fifteen minutes of the class period is taken for written work. The questions are framed in such a way that the papers can be quickly corrected by the student problem readers. Two sets of papers are passed out; these are handed in, and the student on the way out takes a copy of the other set, which he hands in a t the next meeting of the class as a part of his homework assignment. These papers are graded and returned a t the next class period. Students file these papers away in a notebook. From these daily questions the monthly set is assembled. Fundamental concepts are taught by repetition, for after all learning to read is the test of progress and achievement. A critical examination of the simple questions on the daily tests will reveal that a mastery of the textbook language and terms is absolutely demanded. To acquire this real understanding the process of repetition is made the keynote of our efforts. For example, the sheet on the physical properties of chlorine is a repetition of the points stressed in the chapter on changes of state. Students may use their books on the daily quizzes, but not on the monthly quizzes. An examination of these written exercise? will show that only a small part of the student's time is used in the mechanical recording of his answers. True and false, multiple choice, blanks, proble&s, and equations make up the questions. Concert reading of blackboard exercises is introduced occasionally. Semester Grades In mak'mg up the semester grades, the laboratory work counts 25,. the final 25, and the class and quiz work 50 points, to make the numerical value on the scale of 100. A rank sheet is then prepared and is usually found to approximately coincide with the probability curve. The grades assigned, in rough, conform to the rules for grading now in force in .the university: E's less than 5%, S-20%, M-50%, I-20%, F-5%. Our F mortality is considerably higher when students drop out for failure after the six weeks' trial. This year we are trying to salvage more freshmen by holding two extra sessions per week for flunkers. A grade below 50 on a monthly quiz is considered a flunk; fully one-thud of our class of 350 students fall in this class a t mid-semester. Reasons for this high percentage of deficient students are: (1) the courses may he pitched on too high a level; ( 2 ) inadequate high-school preparation; (3) lack of ability-. e., low I. Q.; (4)
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poor habits of study; (5) laziness, lack of application, ability not utilized; (6) system of instruction fails to make an appeal. Sectioning In this connection, the question comes up, should we segregate these "low graders," and give them a course in chemistry more descriptive in character; including something about chemistry and its applicationspandemic chemistry as Bancroft has termed it? Why expend the instructor's time on these students and thus overlook the gifted student? Would i t not be a more efficient plan to give these students a different type of course in which memory work predominates, and containing very few problems? We are still of the opinion that the struggle of the students with the principles is worth more to him than fosteiing smattering, and perhaps developing still further his inferiority complex by the very act of segregation. Students in general chemistry are not sectioned now on the basis of previous training. About 35% of the students in general chemistry have had a course in high school, but we find that only a few of these will take advantage of the option of enrolling for the work of the second semester. About 10 years ago, we separated sections for students who entered with high-school chemistry. Now we differentiate only in the laboratory work, and even in that but slightly. Recognizing that some duplication exists we reduce the credit from five to four*hoursfor those students having had r a high-school course. My observations have convinced me that the duplication which exists does not represent a loss of time in the education of the student in chemistry. In the first place, the lecture demonstration feature of the college course has received but limited attention in the high-school course. Then, too, the college course marks quite an extension of the basic principles. Thus the student with high-school training is not simply marking time when he takes the college course in general chemistry.
~ M Will of Willia'm H. Nichols. According t o Science, the will of the late W ~ L H. N ~ c n o ~ chairman s, of the Board of the Allied Chemical and Dye Corporation, bequeaths $1,000,000 to public purposes. Half of the residuary estate is left t o New York University for the maintenance of the Nichols Chemical Laboratory, which Mr. Nichols gave to the institution in 1927. He served as acting chancellor of the university last spring and fall during the illness of CEANCSLL~R BROWN. It is requested that the bequest be used to keep the laboratory "at all times in good order and repair and well equipped." The largest institutional legacy is 8250,000 to the Polytechnic Institute of Brooklyn. Mr. Nichols attended that school for three years in his youth and was vice-chairman of its board. The American Chemical Society and the American Society for the Control of Cancer each receive 550,000.
