Weekly or Biweekly Quizzes in Organic Chemistry: Does it Make a ~ifference? Robert C. Duty Illinois State University, Normal, IL 61761 There have been manv owinions about how best to teach organic chemistry. ~ m i t hfor , ~ example, introduced a break with the traditional lecture system: his aowroach was to discard, for the most part, thelectures. ~ e c o n t e n d e dthat a certain amount of material doesn't need to be covered in 50 minutes and that the teacher should merely direct the discussion generated hy the students. This approach was motivated by Nash2 who believes "teachers do not teach; at most they stir students to learn." However, this awwroach mav be disastrous for a voluminous subject such as or&ic chemi&, especially if students are expected to take a standardized test in organic chemistry or complete an entrance exam for a dental, medical, or veterinary school. The two-year study described in this paper was begun to ascertain if the frequency of quizzes had a significant effect on learninr. Was testine on a weeklv basis more efficient than a quiz given every two weeks? In a weekly quiz format 19.4% of the lecture time is consumed for testine. For a biweeklv auiz format only 13.8% of the time is used fk testing. Is this'increase in lecture time reflected in a better grasp of organic chemistry? The parameter used to test this hypothesis was the Standardized ACS Organic Examination (1974 Form). This test was chosen because GowenlockQha shown previously that this objective test did show a good correlation with two intelligence tests he used in his studies in Great Britain. He also noted that the organic objective test did not have a deleterious
'Smith, R. B. J. CHEM.EDUC., 44, 128 (1967). 'Nash, L. K., J. CHEM.EDUC., 43, 339 (1966). 'Gowenlock, 6. G., Mclntosh, D. M., and Mackaill, A. EOLIC., 50, 139 (1973).
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W., J. CHEM.
effect on the performance of the verbally more able students. Consequently, we were confident that this test could measure a difference in comprehension of organic chemistry. We did not deviate from the 50-minute lecture format but conducted the organic class in the traditional manner with lectures three times a week and with the accompanying organic laboratory. The first semester the students had a three-hour laboratory once a week, and the second semester they had a three-hour laboratory twice a week. In order to insure that the two classes would cover the same material, the same text (Morrison and Boyd, third edition) was assigned, the same syllabus was followed, the same number of hour exams (one per month) were given, hut the frequency of quizzes was altered-one year quizzes were given every week, and the second year they were given every other week. No quizzes were given during the week of an hour exam. During the first year, 103 students completed the full-year course, and the second year a total of 97 students finished the
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second semester. The class grading scale through both years was exactly the same. This grading scale was 85%-A, 75%-B, 65%-C, and 55%-D. The distribution of grades for both years is shown ~ In Table 1. The grades were calculated from t h stndmtq' performance on h k r exams, quizzee, and the final exam. The nercenkes assigned to each of these were-hour exams.,48%:, quizzes, 32%; add final, 20%. The classes were informed at the beginning of the last semester that a standardized organic exam would he given as their final exam, and each class was guaranteed that the standardized exam would be curved so as to generate a3 many A's, B's, etc., as occurred in their previous four hour exams. ~
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Grade Distribution for Organic Classes
Table 1.
1st Year
2nd Year
22 31 38 9 3 103
15 27 36 19 0 97
A B C D F Total Population
Table 2.
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Percentile Rankings of ACS Standardized Organic Examination for Two Undergraduate Classes
Percentile Rank
1st Year (QuizlWk)
Percent of Total
2nd Year (Qi~izlZWks)
Percent of Total
0-25 26-50 51-75 76-85 86-99 TOTAL
14 27 25 10 17 103
13.6% 26.2% 34.0% 9.7% 16.5%
31 24 24
32.0% 24.7% 24.7% 7.2% 11.3%
Average Percentile Ranking 52.9%
Table 3.
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11 97 45.3%
Syllabus for Organic Chemistry
I. Flrst Semester A. Structure, Properties, &Hybridization B. Hydrocarbon Chemisny-Saturated & Unsaturated C. Stereochemistry 0. Aromatic Chemistry E. Alkyl Halides & Alcohols F. Ethers, Epoxides, & Carbaxyiic Acids 11. Second Semester A. Aldehydes, Ketones, & Carbanion Chemistry B. Amine Chemistry
F. G. H. I. J. K.
Electrocyclic Reactions Polynuclear Aromatic Chemistry Heterocyclic Chemistry Macromolecular Chemistry Fats & Carbohydrates Amino Acids & Proteins
preprofessionals, and the second year there were seven. The scores of the standardized ACS Organic exam are shown in Table 2. The results are entered by percentile scores achieved by students. The difference in average percentile rankings for the two classes is quite significant (7.6%),and this leads one to believe that frequency of quizzes does force the student into a study pattern which generates a higher learning efficiency and concomitant higher rankine. One can argue - that - oercentile . a more gifted class could raise the percentile ranking by this degree, hut a closer check of the percentile rankings reveals an opposite trend for these two classes, e.g., if you compare the number of students below 10 uercentile you will find a sipnificant difference; one student for the frequency of one quiz per week and eight students for the one quiz per every two weeks. There were more students who exceeded the 90 percentile level in the one-quiz-per-week group (16) than in the one-quiz-per-two-week group (ll), hut the difference was not as dramatic as for thelower 10 percentile group. Quizzes were administered at the beginning of a lecture and would last for 20-30 minutes. Students were permitted to make up a quiz with an excused absence hut were given a different quiz if a retake was permitted. Retakes were essay quizzes, and very few were administered (less than one percent). Oreanic chemistrv is a voluminous subiect which requires " a tremendous amount of recall. Consequently, the weekly auizzes ~ r o v i d ea learning vehicle that helm the student re-
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nois State, is taught from a mechanism viewpoint. 6reaction is oresented to a class unless a reasonable mechanism can be presented. A brief syllabus that is used in the organic course is oresented in Table 3. The text, Morrison and Boyd, is covered entirely except for the last chapter, which deals with molecular hiology. This chapter is covered superficially hecause the majority of the students will continue into a biochemistry sequence. The sequence of lecture material follows the chapter designations in Morrison & Boyd. Every attempt is made to present the material in such a manner that the student does not have to jump ahead in the text to comprehend the lecture material. The excention to this rule is on soectroscorw. ----~~ ~pectroscopyt o p i c s A ( l NMR, ~, UV, and mass spectrometry) are covered in the laboratory and are not covered as topics in the lecture. ~
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Conclusion
I t was hoped that this inducement would generate a desire to study for the final exam and eliminate a common feeling among students that performance on a standardized exam is not imoroved hv study.
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plines with allied health professions predominating over disciplines such as psychology, agriculture, and home economics. The preprofessional people (premedical, predental, etc.) also populate the course. In the first year there were eight
The results of this study has convinced this author that a weekly quiz, compared to a frequency of one quiz every two weeks, is an excellent pedagogical tool to stimulate learning in an organic chemistry course which runs for a full year. The difference in average percentile rankings (7.6%)for two classes which were taught from the same syllabus and the same text, Morrison & Boyd, was chosen as the parameter for judging organic chemistry knowledge attainment. The large population (97 and 103) of the two classes should be sufficient to support our conclusion where average rankings do represent a significant difference in the two classes.
Volume 59
Number 3
March 1982
219
