AUGUST, 1949

A COMPARISON OF TEACHING METHODS

THE criticisms of the methods of teaching inorganic chemistry have been widespread.' The lecture, the recitation, and the laboratory have $1 received a share, and the claims and counterclaims have by no means subsided. In so far as the laboratory is con- cerned, the lecture-demonstration as a substitute for individual laboratory method is familiar to all. The effectiveness of the formal lecture has been disputed repeatedly, and in. some instances this phase has been greatly modified. 'Furthermore, as in the case of the lecture, the amount and nature of the recitation hours have been a point of wide disagreement. In short, the search for effective, efficient methods of teaching in- organic chemistry is as intensive as ever; certainly the importance of this search is great enough to demand the careful examination of all pieces of evidence.

In September, 1946, the rapid increase in enrollment a t the Iowa State College compelled the establishment of an annex a t Camp Dodge some 30 miles from the campus. This annex was equipped to accommodate approximately 340 male freshman students, the large

3. STANLEY AHMANN . . Iowa State Colle'ge, Ames, Iowa

majority of whom vere enrolled jn the engineering division. Although facilities and staff were similar in most respects to those of the main campus, limitations of classroom space made it necessary to alter the method of instruction of beginning inorganic chemistry, thereby affording an excellent opportunity for comparison.

At the annex the course was taught by the recitation- laboratory method which consisted of six contact hours per week divided into three two-hour periods. The recitation and laboratory were carried on simultane- ously, thereby providing a much closer contact between the students and the instructor. Although no time was specifically allotted for lecturing, the instructor had the liberty of introducing each class meeting in that fashion. In addition, he was able to divide the laboratory period between the assigned laboratory exercise and oral dis- cussion as he so desired.

One instructor taught each class a t all three meetings and the class size ranged from 25 to 30 students. The students were seated around low laboratory desks. Each student was provided with the necessary chemicals

410 JOURNAL OF CHEMICAL EDUCATION

- and equipment so that it was unnecessary for him. to To test whether or not this difference between the leave his place. In order to conserve time a pan means was significant a t-test was made, yielding a balance was provided for each pair of students. To value of 1.60. This value being nonsignificant, it can be conserve chemicals and apparatus all experiments were said that, if student ability is disregarded, a significant conducted on the semimicro scale. difference in achievement did not exist when the course

Meanwhile, the lecture-recitation-laboratory method was taught by the two methods. used at the main campus consisted of seven contact However, a more sensitive test of significance was hours per week divided into two one-hour lecture available. In the first place, previous studies a t the periods, two one-hour recitation periods, and one three Iowa State College and elsewhere have shown that hour laboratory period. The 'lectures consisted of veteran students achieve significantly better in college formal discourses which contained most of the subject than nonveteran students, and that freshmen having matter to be covered and frequently included labora- .completed courses in high-school chemistry achieve tory demonstrations illustrating various principles of significantly better in first-quarter inorganic chemistry inorganic chemistry. For the most part the recitations than those who have not. In accordance with these were confined to oral review of the lectures and text findings, both groups were carefully stratified into four assignments, question and answer periods, and ad- subgroups, the respective subgroups being equal. ministration and discussion of examinations. The Furthermore, the differences of ability among the laboratory classes were devoted to assigned experiments students can be controlled by utilizing aptitude and conducted on a semimicro scale as described in the achievement scores. Therefore, the scores on the laboratory textbook. American Council on Education Psychological Exami-

The class size varied greatly, ranging from 100 to 150 nation were used as a scholastic aptitude control, the students per class for the lecture and laboratory classes, high-school grade averages as a prior achievement con- and from 20 to 30 students per class for the recitation trol, and the college algebra final examination scores as a classes. There was no assurance that each student concurrent achievement control. The effectiveness of would be taught by the same instructor at the lecture, these controls is evidenced by a multiple coefficient of recitation, and laboratory meetings. A student may correlation of 0.63. Analysis of convariance with mul- have had one instructor for all three phases or as many tiple classification was then computed and the per- as three instructors, each teaching one phase. Further- tinent results are shown in Table 1. more, the lecture, recitation, and laboratory exercises were conducted in different rooms, all of which were of Table 1 sufficient size to accommodate the class sizes previously ~ ~ ~ l ~ ~ i ~ of covariance k t h Multiple classification of mentioned. The laboratory was equipped with individ- Chemistry Nnal Examination Scores ual lockers, general reagent shelves, and balances. Source of D e w s of Sum of Mean

It was easy to compare the effectiveness of the two variation freedmn squares square t methods since similar teaching cond.itions existed in Method 1 47.510.-' 47.510 0 . 5 Z both cases. The same textbook and laboratory manual Within 283 .49,422.251, 174.637 . . .

were used. Classroom facilities and laboratory equip- ment were adequate. All instructors had previous The t value is nonsignificant. Therefore, in so far as teaching experience, but no previous experience with (1) scholastic aptitude was controlled by ACE raw the teaching method employed, a t the Camp Dodge scores, (2) prior achievement was controlled by high- Annex. school grade point average, (3) concurrent achievement

The same weekly examinations aria the same final was controlled by the college algebra final examination examination were administered to all classes. This scores, and (4) no other pertinent factor related to final examination, which was used as the criterion of achievement in introductory chemistry contributed a achievement, was prepared by the member of the staff bias, the two methods for teaching introductory chem- who conducted the lectures in the classes following the istry to freshman students in engineering were con- lecture-recitation-laboratory metbod. sidered to he equally satisfacbry.

A group of 147 male engineering freshmen who were Although the statistical analysis indicates the fore- taught by the recitation-laboratory method and who going conclusion, the Chemistry Department con- had no previous college chemistry experience were com- sidered many features of the recitation-laboratory pared to a group of equal size who met the same quali- method so desirable that they have been incorporated fications and who were drawn a t random from those into the teaching methods of many freshman classes. taught by the lecture-recitation-laboratory method. It would be of interest to duplicate the investigation The mean final examination score for the recitation- here reported under normal campus conditions and with laboratory group was 77.12, while that of the lecture- instructors who have had experience with the recitation- recitation-laboratory group was 80.22. laboratory method of teaching.