AUGUST, 1949
A COMPARISON OF TEACHING METHODS 3. STANLEY AHMANN .. Iowa State Colle'ge, Ames, Iowa
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criticisms of the methods of teaching inorganic majority of whom vere enrolled jn the engineering chemistry have been widespread.' The lecture, the division. Although facilities and staff were similar in recitation, and the laboratory have $1 received a most respects to those of the main campus, limitations share, and the claims and counterclaims have by no of classroom space made it necessary to alter the method means subsided. In so far as the laboratory is con- of instruction of beginning inorganic chemistry, thereby cerned, the lecture-demonstration as a substitute for affording an excellent opportunity for comparison. At the annex the course was taught by the recitationindividual laboratory method is familiar to all. The effectiveness of the formal lecture has been disputed laboratory method which consisted of six contact hours repeatedly, and in. some instances this phase has been per week divided into three two-hour periods. The greatly modified. 'Furthermore, as in the case of the recitation and laboratory were carried on simultanelecture, the amount and nature of the recitation hours ously, thereby providing a much closer contact between have been a point of wide disagreement. In short, the the students and the instructor. Although no time was search for effective, efficient methods of teaching in- specifically allotted for lecturing, the instructor had the organic chemistry is as intensive as ever; certainly the liberty of introducing each class meeting in that fashion. importance of this search is great enough to demand the In addition, he was able to divide the laboratory period between the assigned laboratory exercise and oral discareful examination of all pieces of evidence. In September, 1946, the rapid increase in enrollment cussion as he so desired. One instructor taught each class a t all three meetings a t the Iowa State College compelled the establishment of an annex a t Camp Dodge some 30 miles from the and the class size ranged from 25 to 30 students. The campus. This annex was equipped to accommodate students were seated around low laboratory desks. approximately 340 male freshman students, the large Each student was provided with the necessary chemicals
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and equipment so that it was unnecessary for him. to leave his place. I n order to conserve time a pan balance was provided for each pair of students. To conserve chemicals and apparatus all experiments were conducted on the semimicro scale. Meanwhile, the lecture-recitation-laboratory method used at the main campus consisted of seven contact hours per week divided into two one-hour lecture periods, two one-hour recitation periods, and one three hour laboratory period. The 'lectures consisted of formal discourses which contained most of the subject matter to be covered and frequently included laboratory demonstrations illustrating various principles of inorganic chemistry. For the most part the recitations were confined to oral review of the lectures and text assignments, question and answer periods, and administration and discussion of examinations. The laboratory classes were devoted to assigned experiments conducted on a semimicro scale as described in the laboratory textbook. The class size varied greatly, ranging from 100 to 150 students per class for the lecture and laboratory classes, and from 20 to 30 students per class for the recitation classes. There was no assurance that each student would be taught by the same instructor at the lecture, recitation, and laboratory meetings. A student may have had one instructor for all three phases or as many as three instructors, each teaching one phase. Furthermore, the lecture, recitation, and laboratory exercises were conducted in different rooms, all of which were of sufficient size to accommodate the class sizes previously mentioned. The laboratory was equipped with individual lockers, general reagent shelves, and balances. It was easy to compare the effectiveness of the two methods since similar teaching cond.itions existed in both cases. The same textbook and laboratory manual were used. Classroom facilities and laboratory equipment were adequate. All instructors had previous teaching experience, but no previous experience with the teaching method employed, a t the Camp Dodge Annex. The same weekly examinations aria the same final examination were administered to all classes. This final examination, which was used as the criterion of achievement, was prepared by the member of the staff who conducted the lectures in the classes following the lecture-recitation-laboratory metbod. A group of 147 male engineering freshmen who were taught by the recitation-laboratory method and who had no previous college chemistry experience were compared to a group of equal size who met the same qualifications and who were drawn a t random from those taught by the lecture-recitation-laboratory method. The mean final examination score for the recitationlaboratory group was 77.12, while that of the lecturerecitation-laboratory group was 80.22.
JOURNAL OF CHEMICAL EDUCATION
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To test whether or not this difference between the means was significant a t-test was made, yielding a value of 1.60. This value being nonsignificant, it can be said that, if student ability is disregarded, a significant difference in achievement did not exist when the course was taught by the two methods. However, a more sensitive test of significance was available. I n the first place, previous studies a t the Iowa State College and elsewhere have shown that veteran students achieve significantly better in college than nonveteran students, and that freshmen having .completed courses in high-school chemistry achieve significantly better in first-quarter inorganic chemistry than those who have not. In accordance with these findings, both groups were carefully stratified into four subgroups, the respective subgroups being equal. Furthermore, the differences of ability among the students can be controlled by utilizing aptitude and achievement scores. Therefore, the scores on the American Council on Education Psychological Examination were used as a scholastic aptitude control, the high-school grade averages as a prior achievement control, and the college algebra final examination scores as a concurrent achievement control. The effectiveness of these controls is evidenced by a multiple coefficient of correlation of 0.63. Analysis of convariance with multiple classification was then computed and the pertinent results are shown in Table 1. Table 1 ~ of covariance ~ lk t h Multiple ~ ~classification i of ~ Chemistry N n a l Examination Scores Source of D e w s of Sum of Mean variation freedmn squares square t Method 1 47.510.-' 47.510 0.5Z Within 283 .49,422.251, 174.637 ... ~
The t value is nonsignificant. Therefore, in so far as (1) scholastic aptitude was controlled by ACE raw scores, (2) prior achievement was controlled by highschool grade point average, (3) concurrent achievement was controlled by the college algebra final examination scores, and (4) no other pertinent factor related t o achievement in introductory chemistry contributed a bias, the two methods for teaching introductory chemistry to freshman students in engineering were considered to he equally satisfacbry. Although the statistical analysis indicates the foregoing conclusion, the Chemistry Department considered many features of the recitation-laboratory method so desirable that they have been incorporated into the teaching methods of many freshman classes. It would be of interest to duplicate the investigation here reported under normal campus conditions and with instructors who have had experience with the recitationlaboratory method of teaching.
