Keith M. W e l l m a n
University of Miami
Coral Gables, Florida 33124
Computer Grading of Introductory Organic Chemistry Laboratory Results
Those familiar with handling laboratory sections are aware of the problems of grading. Frequently the support teaching personnel, usually graduate teaching assistants, is spread too thin to do an adequate and fair job of grading with consequent downgrading of the laboratory experience. This is particularly unfortunate in organic chemistry since it is often the first exposure a student has to synthetic chemistry. On the other hand, the conscientious teaching assistant may he burdened with long hours of grading in addition to laboratory contact time. A common but unsatisfactory recourse at this point is to grade during the laboratory. As a solution to this problem we have developed a computer grading system (LABGRD)' which performs three functions. It provides uniform grading, greatly reduced manual grading time, and an introduction to computers for the student. The latter point is achieved by having the students keypunch their own experimental data. In designing this computer program several points were kept in mind. First, the p r o p m should he versatile and amenable to change in order to handle the variety of chemical experiments encountered. This versatility is achieved by having the main program read the student's desk number, experiment number, and data, whereupon a subroutine peculiar to that experiment is called for grading. This scheme also provides flexibility to vary experiments as desired. Second, it should guard against extraneous input data arising from keypunching errors by inexperienced students. It is particularly important that the students not be penalized because of faulty keypunching. Spurious student input is detected by placing limits on the data. Input falling outside these limits causes an error message to be printed for that particular experiment. Third, such a program should print grade output in a manner suitable for posting after each laboratory. At the University of Miami the students are permitted to work on experiments a t their own pace within limits; hence, the posting of all laboratory grades serves to keep the students informed of their progress. Since LABGRD also averages the grades for each experiment, the student can also determine his relative performance. Fourth, in addition to grading the student's data, it is desirable to analyze the data for trends-normal or abnormal. For example, in an experiment involving distribution of several unknown compounds for study, one wishes to know if students with a particular unknown are consistently being penalized because of Several systems for computer grading of examinations hme been reported (1-6). Two other schemes for laboratory oomputer grading have been reported (6,6).
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Journal of Chemicol Education
impure reagents furnished by the laboratory stockroom. At the present time this data analysis is done by a separate program since its incorporation into the main program would reduce the latter's flexibility. Fifth, the input format to he followed by the beginning student should be kept as simple and as uniform as possible. The student input data which we have found satisfactory for many experiments include the following items: desk number, experiment number, unknown number, grams of limiting reagent, calculated moles of limiting reagent, grams product, calculated moles of product, per cent yield, index of refraction, initial boiling point or melting point, final boiling point or melting point, density, qualitative tests (normally three, hut more if desired). Upon submission of the student's keypunched Hollerith card and product, the teaching assistant keypunches further data concerning the purity of the student's product. Finally, if desired, an instructor's grade for graphs, answers to questions, laboratory notebook, and student's attitude can be keypunched on the input card. This latter grade can be weighted a t the instructor's discretion to give varying degrees of "pure" computer grading. Presently, the main program will handle the typical chemistry experiment involving synthesis, isolation, and purification, and qualitative tests. To those familiar with computer programming, it is a simple matter to adjust the input format to handle kinetic or equilibrium constant data. Although the program described herein is for an organic chemistry laboratory, we feel a similar approach would be applicable to any chemistry laboratory which had computer facilities convenient to the department. The procedure greatly reduces the time required for grading while stimulating undergraduate interest in computers. By thevery nature of the modern computer makeup, the student's awareness of the importance of precise data recording comes into sharp focus early, and, perhaps most importantly, the student rapidly comes to recognize the criteria of sample purity and the importance of good laboratory technique. He also learns to evaluate whether it is worth the time and effort to further purify a sample in order to achieve perfection-an excellent training for similar problems encountered in research activities. A listing of our current computer program in Fortran IV is available on request. Literature Cited (1) H r ~ c a f i s rC. , C., *no L*aowsuz, J. I.,J. CHEW.EDUC., 45, 575 (1966). Fmasnro. N. A . . J . Cxsla. Eouc.. 44, 413 (1967). (3) MANN.J. A., JR.. ZEITLIN. H., A N D DELFINO. A. B., J. CHEU.EDUC.. 44, 673 (1967). ( 4 ) YANBT. N. D.. J. C H ~Eouc.. . 44. 677 (1987). (5) Ammauso. 3. F.. AND KIN.. L. A,. CAMPBELL. C.. J. CHEW.EDOC.. 46, 615 (1968). (6) CHAPPBGG. G . A.. &ND MILLDB. R. M.. J. CREM.Enoc., 18.79 (1968). (2)
