G. R. Bakker, 0. 1. Benfey, and W. J. Stranon
Earlham College Richmond, Indiana
Programing as an Aid to Effective Chemistry Teaching
The "teaching machine" is of course nothing new-we have seen it in the form of flash cards for language instruction and in the toys of our childhood which light up when the contact device touches the correct button. These were devices that someone markekd and the teacher in school and college used them if he liked them. No evidence went with them claiming to prove that they aided the teachmg process. What is relatively new about self-instruction devices --of which the ordinary hard cover book is still and is likely to continue to be by far the most prevalent-is the application of approaches characteristic of scientists to the development, modification and evaluation of such devices. Statistical analysis is available with all its power and pitfalls to give an indication whether learning has in fact improved. I n addition the subjective responses of students and teachers can he elicited to help determine whether learning by means of self-instructional devices has been more efficient, enjoyable, and effective. Early enthusiasm cannot, however, be taken as proof of success, particularly if the student,^ know that they are guinea pigs in an experiment. Earlham College has experimented with self-instruction devices from tape-recorders used to improve foreign language pronunciation, to "Skinner machines" and mimeographed materials in a dozen or so liberal arts fields. The work was supported in part by a grant from the Department of Health, Education and Welfare' and was organized under a director conversant with developments in the suhject and with research in the psychology of the learning process. The chemistry department was intrigued with the possibility of (I) developing instructional materials on particular topics which an instructor may safely assume is known by a large majority of the class hut which some students may not have mastered in high school (or earlier college courses). Examples are the use of exponents and logarithms, the writing and interpretation of molecular formulas, and the balancing of simple chemical equations. With these programs students who have had inadequate or no previous high school instruction in the subject can bring themselves up to the level of those who have. Students familiar with the material can discover a new approach to it and may learn a clear, logical development of the ideas on which a solid college course can then he built. Such materials might also be useable on the high school level. We also wished ( 2 ) to simplify instruction in topics that might he called the scaffolding of chemistryPresented at the Symposium on Programed Instruction at tho 124th Meeting of the American Chemical Society, Atlantic City, New Jersey, September, 1962. 1 Grant No. 7-12-026.00, United States Office of Education, Department of Health, Education, and Welfare.
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Journal of Chemical Educaiion
topics not very significant in themselves, but needed in order to simplify the later discussion of chemical systems. Examples are the writing of Lewis structures (electronic formulas), ionic and oxidation-reduction equations, the computation of "formal charges," the unambiguous naming of organic compounds and the writing of isomeric structural formulas. The proper procedures for carrying out such assignments require very careful following of directions in a stepwise fashion. Such directions are usually only imperfectly learned through lecture presentations, textbook assignments, or problem sets. I t was thought that programed instruction in these topics might be able to transmit the proper steps in a way which would assure mastery of the simpler stages before more complicated problems are attempted. We were also interested in seeing (3) whether programed instruction is as useful in advanced chemical discussions as it seems to be in the beginning stages. We have prepared a program for calculations based on volumetric analyses and one dealing with colligative properties of solutions. A fourth goal, (4) the exploration of the use of prelaboratory, laboratory, and post-laboratory instruction, has us most puzzled a t the moment. We have made some progress with pre-laboratory instruction, our purpose being to demand that the student has thought through the background or theory of an experiment before entering the laboratory. We do not see at the moment how laboratory work itself can he programed except for essentially foolproof procedures where the answers are completely known. Programed laboratory work runs counter to another trend in laboratory instruction, which emphasizes the investigative approach and is based on the premise that the greenest freshman may, by careful observation, discover somethmg new. Some programing work currently being carried out at Earlham in the Chemical Bond Approach (CBA) Project suggests that a simple experiment with a prescribed kit might be used as an introduction to the development of classroom material. Thus a set of electrostatics experiments may serve as a first-hand basis for the development of electrostatic concepts. It is of interest to note that we have become more convinced of what should be obvious to all chemistry teachers, namely that learning in chemistry cannot proceed very far without knowledge of the physical system, without laboratory experience. Preparation of Programs
Our programs so far, except for the recent ones developed in the CBA Project, have been of the Skinner or linear constructed response type. Their general
nature has been described by Y o ~ n g . We ~ have kept open the question o f an optimum error rate, being concerned not to make the steps so simple as to insult the student's self-respect. We have used programing more for the exercise of logic than for simple memorization. If something has to be memorized, apart from a few mnemonic aids, we doubt if we can provide much help on the college level. We think that much direct memorization can be hypassed by supplying and using the terms to be memorized often enough, so that the st,udent will know them without conscious effort. We are beginning to see uses for multiple choice forms of answers and for branching and looping programs, that is, the supplying of further instruction to students who missed a given frame; and we will probably attempt cornhinations of multiple choice and constructed response items in the future. We would insist that the value of constructed responses is that the student supplies the answers. Instructors who give only multiple choice examinations are likely t,o lose any conception of the number of different ways his students can go wrong. We detail below some of the informat,ionobtained from an analysis of st,udent responses. The most common procedure for preparing programs has been the following: (1) The separate items are typed an pages of Gin. X 6-in. paper pads. Having items on separate pages permits easy replacement or addition of further items. (2) The program is checked by two or three students. (3) The program is cheeked b,v one or marc chemistry colleagues. ( 4 ) I t is revised, possibly rechecked, and mimeographed in linear sheet form. (5) The mimeographed program (to be used without machines) is submitted to one or more classes for testing. (6) Erroneous answers are listed and analyzed, and error rates are computed and plotted. ( 7 ) Items are analyzed in the light of comments and test results, and n revised version is prepared.
In the development of programs it is important to know accurately what the student knows before he works through t,he program and what he has gained by the pbcess. The written responses are usually insufficient to pinpoint the difficulties. Often, questioning of students who have worked through the program will help hut pre- and post-testing is necessary and in the development of the programs ought to be extensive. Where possible, we feel that the program should be tested also in another institution. Aids to Effective Chemistry Teaching
Assuming that in principle programed instruct,ion is a usefnl t,eaching aid, responses from individual students and error rate data can be used to improve such instruction by expansion, correction, and the removal of ambiguities. A program on oxidation-reduction equations originally had an average error rate of 9% (tested on 30 sophomores). After revision the following year, a class of 25 sophomores supplied answers with a 7% error rate, which may he a chance variation; hut the error rate for the last ten items dropped from 15 to 4%. When the same program was given to a group of freshmen, however, the error rate was considerably
higher (16%). This may only be due to the broader range of students involved but it may indicate that something like general chemical maturity and greater ease in handling a technical language are significant in learning materials for which both groups were thought to have an adequate specificbackground. Programing forces the teacher to become aware of the complexity and inner logic of a topic he may have thought of as simple and straightforward. Thus the idea of formal charge, on mhich perhaps half an hour is usually spent in class, and which students notoriously do not master, required the following concepts for its systematic presentation: structural formula charge concept of "formal" charge as a first approximation shared electrons concept of equal sharing algebraic sum of positive and negative charges proton, electron, nucleus, atomic number, nuclear charge inner shell atomic kernel kernel charge Lewis structures (showing only outer "valence" electrons the atomic symbol standing for nucleus plus inner complete electron shells) law: sum of formal charges = charge an particle as a whole (zero for molecules, ionic charge for ions) lines to represent electron pairs: alongside atom symbol ii unshared, directed away from ntom symbol if shared.
The above list of concepts mas used in a program of 40 frames designed to teach the student how to calculate formal charges when the detailed electronic structure mas supplied. Instruction in the writing of such structures involved another 47 frames and required a further set of concepts. The formal charge program was remarkably successful. In an unannounced post-test sprung on the students a few days after completion of the program, with no instruction or discussion of the subject whatsoever, 21 out of 23 freshmen gave the correct formal charges for the atoms of
Training in the writing of Lewis structures was not so successful. In a question in the same post-test: "Write the electronic formula, showing both shared and unshared outer electrons, for hydraaine, HINNH2," 14 out of 23 students gave the correct answer. The others gave the identical wrong answer:
The rule of two seems to have been learned, the octet rule not at all. Here seems to he an ideal place for a branching program! Some teaching prohlems are highlighted by programs hut are not easily solved by program revision. Figures 1 and 2 show the error rates for a program on th? systematic naming of alkanes given to freshmen at Earlham College and in the nursing curriculum of the University of Illinois at Navy Pier re~pectively.~Item 11 mhich stands out in both figures was ambiguous and was easily corrected. Items 33 and 35 on the other hand were the most difficult naming problems, but were thought to 3 We are indebted t o Profemor Joan M. Jones of the University of Illinois a t Navy Pier for supplying this information.
Volume 40, Number 1 , lonuary 1963
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he solvable on the basis of earlier instruction. It may be of interest to notice that whereas the general error rate in Figure 2 exceeds that in Figure 1, the error rates for items 33 and 35 are markedly lower in the second case. This is probably evidence for something many have suspected, that the making of mistakes helps in the learning process if the errors are immediately recognized, and that a more difficult program with which a student has to struggle will teach him more than one he can breeze through. A student who skims over the preliminary material is likely to find difficulty with a later item requiring the use of much of the earlier information. Clearly the error rates for items 33 and 35 were too high. Item 33 asked for the Geneva name of the hydrocarbon whose skeleton is C C C C C - C C C C - C C
r
In place of the correct answer (5-methyl-3,5-diet,hyldecane) some erroneous answers read: 5-methyl3,5-ethyl3-ethyl-5-methyl-5-ethyl3-ethyl-5-methylethfl5-methyla-ethyl-5-ethyl-
(3 students) (2 students) (2 students) ( 3 students)
In addition three answers were based on heptane as the parent hydrocarbon and t,hree on octane. There were 29 student responses in all. Clearly the problem here is the application in t,he right order of a series of detailed and somewhat arbitrary rules. The names listed above are all unambiguous; they can only refer to the substance represented by the formula, but t.hey are not t,he correct name. Reference works do not list them. Something was learned from the mistakes here, for in the last item, asking for the formula of
the error rate was down to 14%
Item 35 asked for the name of (CH8CHz),C. Eight out of 29 students left it blank, four simply called it nonane and the total error rate was Xfi'%. The responses to a number of other questions have led us to believe that one of the difficulties students face in organic chemistry is the deciphering of such condensed formulas. In the revision of the alkane program an attempt was made t,o lead up to the most complex items more slowly and to emphasize the process of deciphering. The attempt was only partially successful. The error rate for the diethylpentane item dropped from 86 to 61i%. The 5-methyl-3,5-diethyldecaneframe mas made the last item in the program where it was missed by 73y0 compared with the earlier 65%! There may be a real problem in using linear programing for "synthetic" conceptual learning, the combining of items of material from many differentpoints in the program. We have found programing so far most satisfactory in very tightly knit subject matter, connected by logic, arbitrary rules, or both. Correct word answers seem to be elicited with much greater difficulty (unless supplied in the same or the previous frame) than numbers, symbols, formulas, and proper names (as in naming systems). If one can generalize from our experience one might predict t,hat linear programs requirmg written responses are likely to be most successful with mathematical topics or subjects that can he put in symbolic form, i.e., that are amenable to the approaches of modern algebra. One of t,he widely-advertised advantages of selfinstruction is that it is truly individualized instruction. We have become convinced that if this advantage is to be obtained it is folly to expect one program to teach a given body of material to all students of whatever background and intelligence. Programs are individualized instruction only if they are designed for a particular group of fairly homogeneous students. Self-instrnctional devices do not automatically circumvent the problem of boring the bright student and passing by the dull or ill-prepared student by a presentation designed for the average student. In summary, our admittedly limited experience suggest,~ that reasonably short programs on specific topics
ltem Nvmber
ltem Number
F i g w e 1 . Error d a t a for o 3 6 item progrorn on the nomenclotwe of olkoner tested on 2 9 studentsin a liberal artscollege.
Figure 2. Error d a t a for t h e some progrom or in Figure 1. tested on 2 3 sludenh in a university nursing curriculum.
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Journd of Chemical Education
would appear, on the hasis of student and faculty comments, to be the most useful approach to college chemistry programing. This means that programs would not replace a conventional text entirely, but would replace the text (or possibly be used in conjunction with the text) for certain topics. Student comments on programs seem to be generally favorable. There is some
complaint about the tediousness of working clear through a unit. Yet, in spite of this, students apparently feel i t is a useful technique because they have heen asking for more units on other topics with which they have difficulty, such as equilibrium, activit,y coefficientsandresonance.
Volume 40, Number I , January 1963
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