RESIDUE of HIGH-SCHOOL KNOWLEDGE UTILIZABLE in COLLEGE CHEMISTRY* PAUL MAURICE GLASOE St. Olaf College, NorthCeld, Minnesota
u p of 186 questions, gave results i n very close accord with the performance i n the tests. Due notice i s taken of the presence of a few nonyreshmen students i n both courses, the two groups are compared as to native ability by the Minnesota college afititude test, and finally the scholastic achimement of all the students inwolwed i s measured by the gradepoint ratio. The conclusion i s d r a m that all the results point to a distinct residue of knowledge carried over from high-school to firstyear college chemistry.
This paper recordc a n effort made to evaluate the znpuence high-school chemistry has on first-year college chemistry. The experiment was conducted with two sections numbering about 80 each. Twelwe tests were gigen during the second semester, all of the "short-answer," factual type. The results are remarkably unqoorm, showing without a single exception a decidedly better achiwement on the part of the students who have had chemistry i n high school. The final examination, made
+ + + + + +
I
T IS gratifying to note both from papers read
before the Division of Chemical Education and from articles appearing in the JOURNAL OF CHEMICAL EDUCATION that high-school chemistry is being taken more seriously by colleges and universities. In addition to giving a unit of entrance credit to those who enter with high-school chemistry, colleges are organizing special classes for those who have had it. There is by no means uniformity of treatment by all institutions. The mere division of first-year college chemistry into two classes, one for those who have had and one for those who have not had high-school chemistry, is not sufficient. In 1929, a t the St. Louis meeting of the American Chemical Society, the author of this paper called attention to the "Deadly Parallelism between Courses in High-School and First-Year College Chemistry,"' pointing out the pedagogical error in forcing students with a year of high-school chemistry to go through a year of college chemistry, which is only an elaboration of the high-school course. In 1931 Professor Stuart R. Brinkley2 of Yale presented a paper in which he showed that possible to give a course to such students that will not,be a repetition of the work done in high school, but a consistent development of the general principles of chemistry based on the residue of knowledge we have a right to expect in such students. In view of the importance of a closer coordination between the high-school and college courses i t was to be
'Presented
beforethe Division of Chemical Education at the Denver meeting of the A. C. S., August 23, 1932. ' P. M. GLASOE, "The deadly parallelism between high-school and college courses in chemistry," J. CHEM.Eouc., 6, 50&9 (Mar.. 1929). 2 STUART R. B R I N ~ Y"The , freshman course in chemistry for students who have had secondary-school chemistry," ibid., 8,28&9 (Feb., 1931).
expected that efforts would be made to get some measurement of the influence of a year of high-school chemistry on fust-year college work. Too often college and university teachers express the opinion that i t would be better not to try to teach chemistry in high school, holding that results indicate that little or nothing is carried over from high school to college. Of course, this is an extreme and illogical statement and a grave charge against our whole system of high-school teaching. Either high-school chemistry should be granted the standing of a prerequisite, entitling the college freshman who has had the preparation to a special first-year course, or highschool chemistry should be discontinued. If highschool graduates do not retain a residue of knowledge on which to build their first-year college.course, it is highly questionable that it pays to continue the highschool course even for those who do not go to college. In his two-volume work "The Junior College,'' Dr. L. V. Koos3 has discussed the overlapping of the two courses in question. He has gone into considerable detail to show the parallelism and repetition that take place when a student goes from the high-school course in chemistry to the first-year college course. An exhaustive study was made by Victor H. No114 of "Laboratory Instruction in the Field of Inorganic Chemistry." The thesis covers 164 printed pages. In a brief four pages he makes reference to an observation of two groups of students entering the university a t the same time, one section with high-school chemistry, the other without. His conclusion is that the
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qL. V. Koos, "The junior college," Chap. 33.
4 VICTORH. NOLL,"Laboratory instruction in the field of inorganic chemistry," University of Minnesota Press, Minneapolis, 1930, pp. 104-7. For review, see J. CHEM.E~uc.,8, 606-7 (Mar., 1931).
571
two groups "showed no significant differenc'e after two quarters of instruction in the university." After a careful study of Dr. Noll's problem we are constrained to ask if the results might not have been different had the two sections been treated differently from the start. Should not section A (with high-school chemistry) have been given to understand that they were advanced students by giving them a different textbook, different laboratory manual, and different experiments? All this in order to make the course as much as possible a continuation and not a duplication of the highschool course. In a fair test should not both sections have had exactly the same number of hours of instruc.. Median course 11-12 Median course 21-22 Points of diserenee Percentage gain 21-22 over 11-12
nized as a rehash of what they had done before. Stress was laid on problems and the development of the subject on the basis of the periodic system. In entering upon such subjects as structure of the atom, theory of ionization, reversibility and equilibrium, etc., the high-school treatment of the same subjects was assumed as a foundation upon which to build. The students were told that they would have to review their high-school chemistry in order to be able to keep abreast of the subject as i t was given. It serves as a stimulus for them to know that they are responsible for the knowledge they should have acquired in high school. The second semester was devoted to a syste-~
~
21.7 .24.2 2.5 11.5
11.1 12.5 1.4 12.6
6.8 10.0 3.2 47.0
tion per week? Would not results have been more reliable had both sections been taught by the same person and the quizzes and examinations made up and scored by the same individual? Then, again, we learn that section A was composed of chemists and chemical engineers while B was made up of a diversity of engineering students taking chemistry as a required study. Section A had everything in its favor-they had studied chemistry in high school and pursuit of chemistry was to be their life-work. This ought to make a decided difference in accomplishment. Does the test account for the complete disappearance of this advantage? In January, 1926, Fred C. Mabee6 reported an experiment in which he tested three college first-year chemistry classes and three high schools. His findings will be referred to later in this paper. For the past fifteen years or more I had been confronted by this problem. I had been satisfied from the start that there is a decided influence camed over from high-school chemistry to the first-year college course. I had as yet no definite proof or measure of the residue of knowledge carried over, but faith in the correctness of the reasoning grew to a definite conviction. At the beginning of the school year 1931-32 I decided to ascertain, a t least in some degree, what the influence of the high-school course in chemistry might be. Conditions were favorable. The first-year course was all given by me. With an enrolmqt of 160-170 I could have accurate knowledge of what each student was doing. I conducted all recitations, gave all the lectures, prepared all quizzes, and scored most of them myself. The enrolment for 1931-32 was made up of 85 who had studied chemistry in high school and 79 who had not. The first semester was used for laying the foundation for the beginners in the usual way. The advanced group was given preliminary instruction sufficiently different from high-school chemistry not to be recog-
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F. C. MABEE. "A test of achievement in college chemistry, etc.," J. CHEM.EDUC., 3, iO-6 (Jan.. 1926).
12.3 14.7 2.4 11.4
7.6 11.4 3.8 60.0
12.6 14.6 2.0 15.8
12.8 15.8 3.0 23.4
12.6 14.3 1.7 13.5
22.0 25.4 3.4 15.5
30.0 30.2 6.2 20.6
--
29.2 33.6 4.4 24.0
36.5 38.2 1.7 4.6
matic study of all the common chemical elements in much the usual way, special stress being laid on the periodic arrangement. Both courses were now running parallel. Twelve tests were given a t fairly regular intervals; some were announced in advance, others were not. The tests were of the usual short-answer objective type; such as true-false, completion, matching, and multiple choice. They occupied one recitation period of fifty minutes each. Comparison of the data shown in the above table reveals a remarkable uniformity of results throughout. The table shows the medians of the scores of the two courses and also the percentage of superior achievement of the students in course 21-22* over those in course 11-12. The "percentage gain" was obtained by dividing "points of difference" by the median, course 11-12. The average semi-interquartile range for the twelve tests shows Q = 2.9 for course 11-12 and Q = 3.3 for 21-22. For the purpose of combining the different tests, the scores were all converted to percentile rank scores. The result of thus combining all thedests is graphically shown by curves (A) and (B) of'Figure 1.
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* Course 11-12 is given to those who have not had chemistry in high school; course 21-22 to those who have. , .o
JL.3
a74
ARB BASED ON THE TWO GROUPS, THE
A V E u ~ OF ~ ALL
TAKEN RAWSCORES BEING CHANCED TO PERCENTILE F ~ N SCORES K AND COMBINED
TE,
Curve A-no chemistry in high schwl. Curve B-chemistry taken in high school. Median percentile score "A" 32.3. Median percentile score "B" 59.3.
Without a single exception the course 21--22 sections did a better grade of work than those in course 11-12. The percentage gain of achievement ranges from 4.6% in test No. 12 to 50% in No. 5, the average being 20.8%. The variation in performance within the two groups does not differ to any marked extent as shown by the measure of variability, the semi-interquartile range. For course 11-12 this measure, Q, is 2.9 while for 21-22 it is 3.3. The final examination naturally becomes a test of a great deal of significance. It was composed of 186 questions of the same short-answer, factual type. Two hours is the usual time given, but in this case students were allowed all the time they desired. The questions were mimeographed and a set given to each student. The differences in performance of the two groups are here indicated: Median for course 11-12 was 64.80 Median for course 21-22 was 86.46 Percentage of higher achievement by 21-22 was 33.40 Semi-interquartile range for 11-12 11.23 Semi-jnterquartilerange for 21-22 13.03
The results are graphically shown by the curves of Figure 2.
Referring again to the test reported by Mabee,= three college classes were examined. There was no uniformity as to circumstances. The college A class had not studied high-school chemistry, while classes B and C had. A was examined a t the end of 8 months of study, B a t 41/2, and C, 5 months. The results of the test compare favorably with those just given above: 3
College A B C
nigh-school Chcmislrg No Yes Yen
End of Monihr
Howr on Wmk
Mcdion
8
43.1
4.5
6 9
5
0
Gmde 71.8 62.2
The advautage of B over C undoubtedly can be accounted for by the fact tbat B spent 50% more time each week on the subject. Percentage gain of B over A Percentage gain of C over A
The objection would naturally be raised that the presence of a considerable number of upper classmen
in my study might materially influence the results; these being more mature would naturally be expected to do a better grade of work. To eliminate this factor the performance of the freshmen alone in the two groups has been compared, giving the following results: Median for course 11-12 Median for course 21-22 Percentage higher achievement Semi-iuterquartile range, 11-12 Semi-interquartile range, 21-22
64.0 89.3 39.5 10.6 14.5
Note that the difference in the percentage gained by the 21-22 group is even greater when the nonfreshman students are omitted than when they are included. Another possibility must be taken into consideration. The students of course 21-22 may happen to be of a suoerior made who are more interested in the subiect. use their>me to better advautage, etc. A study oi the grade-point ratio in all the students' work in collegeobtained by dividing the grade points earned by the credit hours taken-tbrows an interesting light on this objection. The scholarship record measured in terms of grade-point ratio for all students taking course 11-12 was 1.17; for course 21-22 i t was 1.28. These figures indicate that there is an advantage in favor of 21-22 amounting to 9.4% in scholarship ratio. This is to be expected, as i t is usually the better grade of student that elects chemistry in high school. But the distinctly better performance of 21-22 in chemistry, amounting to an average of 20.8% for twelve tests and 33.4% for the final examination, can hardly be explained by the slight difference shown in the grade-point ratio of the two groups in college scholarship. -There remains the additional possibility tbat we may have a group of students in 21-22 of superior native ability. To check this point we refer to the results of the Minnesota college aptitude test. The median percentile rank for 11-12 is 28.75, while for the 21-22 group i t is 31.25. Q for 11-12 is 26.55; fos 21-22, Q is om
..
-0
'51.18.
Here we do find a slight advantage in favor of the 21-22 group amounting to 8.6% but certainly not sufEcient to account for the marked difference in their performance in chemistry, which is 20.8% for twelve tests and 33.4% in the final examination. ', As a further point of comparison the records of these same students in qualitative analysis during 19321933 may be cited. Sixty-two students took the course. At the end of the semester six A's were given, all of which went to members of course 21-22. Thirteen B's were given and 73% of them went to members of course 21-22. This would seem to iddicate that the advantage persists. CONCLUSIONS
There is a definite "residue of knowledge" carried over from high-school chemistry to the first-year college course. In order to retain this advantage
students presenting chemistry as an entrance credit closely checked. That the native abilities of students must be treated as an advanced grade and not literally in course 21-22 are very much like those in course made to wait until the section without such preparation 11-12 is seen from comparison of the results of the catches up. The advanced sections must be allowed college aptitude tests for both sections and also by the to build on high-school chemistry as a foundation and general college scholarship ratings as shown in the gradenot made to repeat elementary principles and experi- point ratios. The definite and consistent higher ments covered in the preparatory course. Such a achievement of the students in course 21-22 over those course requires that we do away with the overlapping of course 11-12 as shown in twelve tests and the final to which Dr. Koos3 calls attention. In this way interest examination leads us to the conclusion that the higher in chemistry is aroused and increased rather than achievement is a measure of the influence carried over from high-school chemistry to the first-year college stifled and destroyed. In the present study, intruding factors have been course.
