Evaluation of a Videocassette-Discussion Teaching Format in General Chemistry
John Enger,' Anne T O ~ S - W O O ~ , and Kim Cohn2 University of Illinois Urbana. 6 1 8 0 1
This paper will present an evaluation of the ongoing professionally produced videocassette-discussion teaching format currently employed in introductory chemistry. textbook I"Chemistrv: A Conceotual Aonroach." Mortimer. 19751 wasassigned t i both g r ~ < ~ he s . iive le&er for the traditional mode of instruction had more than 10 vears of experience teaching general chemistry, and based onstudent evaluations was as well received as any previous lecturer in the same position over the past three years a t UIUC. At the conclusion of the semester, a 183-point objective comprehensive final examination was administered to both groups. The students in both groups also responded to questionnaires which are designed to assess student perception of instruction. In addition, TA's associated with each mode of instruction were surveyed by questionnaire to ascertain their perceptions of the effectiveness of the two modes of presentation.
Since 1968 the Chemistry Department of the University of Illinois a t Urhana-Champaign (UIUC) has produced an extensive series of television tapes for courses in introductory chemistry (1). This paper will present an evaluation of the videocassette-discussion oneoine.. . orofessionallv. nroduced . teaching format currently employed in introductory chemistry (21. . . Related studies ducumentinr! the utilization of television in chemical education are presented in an earlier report (3).
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Evaluatlon of the Televised Presentations Freshmen are placed into the introductory chemistry sequence at UIUC by their performance on three measures: (1) their high school chemistry background, (2) their score on the chemistry placement examination, and (3) their score on the mathematics olacement examination. Those who nerform poorly on these measures are recommended to enroll in Chemistw 100 to remove their deficiencies. Those who exhibit exceptional backgrounds are placed inchemistry 107. Most students are advised to enroll in Chemistrv 101. In the fall semester of 1975 both the triditional lecturediscussion and videocassette-discussion teaching modes were used i n Chemistry 101 (General Chemistry ~ e c i u r e )At . registration, sections were not identified by the teaching mode. A total of 1066 entering freshman students completed Chemistrv 101. During that semester 810 students enrolled in 43 sections which used the videocassette-discussion teaching format and 256 students enrolled in 14 sections taught in the traditional live lecture-discussion mud?. There was little crossover after the initial registration with at most 14 students changing teaching modes oily because of schedule conflicts. About 10%of the students registered dropped each teaching mode during the semester. Teaching assistants were randomly assigned to teaching modes with minimal exceptions to the initial assimment arisine" onlv - from unforeseen schedule conflicts. Both teaching modes used the same lecture topics, ohjectives, homework assignments, and order of presentations throughout the semester. Students in both groups were given the course syllabus to follow the lectures. Likewise, the same
Cognitive Measures On entry into Chemistry 101 the two groups of students, those being instructed hy the live lecture-discussion (LL) mode and those viewineand discussine the videocassette (TV) presentations, differed significantly o n only one of the cognitive variables investigated. Note Column 1 in Table 1 in which entry variables such as high school rank, ACT scores, placement test scores, and high school chemistry measures (Variables 3-8) yielded point biserial correlations with the group membership variable (Variable 1where TV = 1and LL = 0) which, with hut the one exception (Variable 4, ACT Mathematics Score), were not significantlydifferent than zero. Thus, the two groups were essentially the same on entry to the course. The exception is not regarded as serious, however, and an explanation is given after presenting one additional findine A significant difference between the two groups was found for the variahle identified as final exam score (Variahle 2). The correlation uf 0.1: is significantly different from zero at the n = 0.01 level of sirnificance which implies there ir a difference in the final examscore distrihutionsof the two groups. The 'Now at Arkansas State University. SNOWat California State College, Bakersfield
Table 1. Correlations and Sample Sizes of Copnltlve Variables in Chemisiry 101 Varlsblea 1 2 3 4 5 6 7 8
Mean SD
1
2 1066
0.17 -0.03 0.08 0.00 -0.01
4
5
6
7
8
1065 1065
1059 1059 1058
1020 1020 1019 1020
1024 1024 1023 1024 989
1019 1019 1019 1019 982 989
1044 1044 1007 1043 1004 1024 1007
0.29 0.36 0.31 0.30 0.41 0.38
0.19 0.06 0.39 0.24 0.09
0.35 0.17 0.50 0.20
0.l8 0.20 0.22
0.18 0.16
0.18
110.6 24.22
89.5 10.06
30.0 2.91
29.5 3.44
4.51 0.59
22.4 5.48
0.01 0.03 0.76
3
25.1 6.48
IYarlabie identificationand range: Variable l-Oarp Membsrahlp (N = 1. U = 0). Variable ?-Final Exam Smrs 10. 1831. Variable 3-High S d w l Rank (as a percentils). Variable Mamematlcs scae 16, 361. Variable 5-ACT Natural Science Smn, 18. 361. Variable 6-Chamistry High Schaol made (A = 5.0). Variable 7-Mahsmatka Placement Test Sowe [O. 401, and Variable 8-Chemisby Plaosment Ted Scae [0.60]. 4-ACT
230 /
Journal of Chemical Education
Table 2.
Freshman Achlevement by Subtest on the Compreherulve Final Exam, Total Points
Subtest Bonding and Elmronlc Srmcture Oxidation-Reduction and Electrochem. Periodlc Properties and Descriptive Chem. Gases. Liquids. Sallds and Solutions Stoichiometry. Adds and Bases Nuclear Chem., Energy, and Coord. Cham. TOTAL A . ~ I ~ l f l c adinerenu, nt was nmed be-
40 20 30 25
41 27 183
N
verws LL
Meana
TV (N = 757) Mdn.
S.D.
Meana
LL (N = 225)
Mdn.
S.D.
24.6 13.3 19.7 15.2 23.6 17.5 113.9
24.9 13.7 19.7 15.2 23.0 17.6 113.1
6.58 3.83 4.70 4.71 7.77 5.12 23.71
22.2 11.9 16.6 13.3 21.4 16.5 103.8
21.8 12.2 18.7 13.5 21.4 17.0 102.0
7.07 4.35 4.69 4.31 7.54 5.18 24.5
each set of meanoat m a p < 0.05 level.
mean final exam score for the TV grouu .was 112.9 and the corresponding mean for the LL group was 103.3. Standard deviations on these scores were 23.7 and 24.4, respectively. Thus on the averaee. hieher scores on the final exam are a;corded to the vide&ass&-discussion group. The inference is that the videocassette-discussion mode of instruction is having a favorable effect on the performance of students. Although group averages on the ACT Mathematics variable were significantly different (with a mean and standard deviation of 30.1 and 2.82 for the TVgroup and 29.6 and 3.14for the LL group), the relationship between group membership and final exam score when partialing out ACT Mathematics statistically reveals that the ACT Mathematics variable has a trivial effect on the relationship of interest. Calculating the partial correlation coefficient among these variables yielded a value of 0.15 which still represents a significant difference between the two groups on the final exam score even when the ACT Mathematics score is held constant. I t might he noted that sampling error theory alone would be expected to explain correlations in the range found for the ACT Mathematics variable when, many correlations are simultaneously computed, as was done with respect to the entry variables. Suhseauent investieation of the final exam scores as shown in Table i has shown student achievement was more effective in the videocassette-discussion mode in each of six areas of instruction than in the live lecture-discussion mode. Thus, the general overall achievement index was indicative of achievement throughout the course and was not weighted by only one or two areas of instruction. Affective M e a s u r e s
At the conclusion of the semester, students in fmt semester chemistrv were asked to evaluate the instruction thev had ~, received by responding to a series of items on a course evaluation auestionnaire. Three different forms of this auestiunnaire were used in the course: the first for evaluatik of the large g r o u ~lectures ~ i v e nin the traditional mode. the second forthe evduation of the TA discussion sessions khich were coordinated with the live lecture. and the third for the evaluation of the televised presentations and TA interaction with these presentations. Tables 3 and 4 compare by the t-test the average student responses to these questionnaires across items. Data presented in Table 3 strongly suggest the TA's are comparable in both the LL and TV modes of instruction when evaluated by the students. Although the responsibilities of the TA's were different under the two instructional modes, students perceived the TA's as performing well. As was stated earlier, the televised material is clear and concise yet proceeds at a more rapid pace than does the live lecture. Students, however, in their perception of the instruction received, rated the pace of the live lectures as being faster and covering too much material. In a large group situation, it is possible that students are forced to follow a traditional 4 5 5 0 minute lecture without being offered the opportunity to ask questions. The videocasette-discussion format, although material at a faster rate, can be stopped, rerun, and accompanied by explanations to suit the needs of the student. ~
~
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Table 3.
Student Percepllon of TA Enectlveness In Chemlstry 101
Questionnaire ltem TA Haldlng Interest TA Encourages Discussion Preparation of TA Oral Delivery of TA
Scale Rangea
.
Mean Responseb TV (N = 817) LL (N = 258)
DullIExcitlmg RareIFreq~~nt
3.76 4.11
3.47 4.15
DisorganiredIWell Prepared AwkwardIEffective
4.06
4.05
3.73
3.69
4.08
4.02
4.34 3.70
4.13 3.66
4.05
4.22
3.86
3.98
TA's Percepllon and UnresponslvelHelptul Hel~ Availability of TA Never/Excellent TA's Abillty to Explain UnsatisfactoryIExceC lent TA's Overall Very P ~ ~ l E ~ c e l I e n l Performance Homework Grading Slow/Prompl
.Scale rango was 1-5 w l h an Wmal suxe of 5. "NOsignificant dinersnces between mesa means m e noted at me p < 0.05 level. Table 4.
Student Perception of lnstructlon In Chemlstry 101 Mean Response
Questionnaire ltem
Scale Range'
TV (N = 817) LL ( N = 222)
Pace of Presemations Too SiowITw Fast Level of Presentations Tao LowlToo High Relevance of Exam terns PaorlExcelient Fair Handling of Grading Seldom/Always Reouests Tefibook Unsatisfactory1 Excellent Level Of PWOnaI EffMt LOwIHigh Motivation to Learn Adver~elExcellem Insight and Understanding Adverse/Exeellent Expected Lener Grade FeilurelExcellent
3.97= 3.41 3.10 3.60r
4.15c 3.6gr 3.24 4.060
2.97b
3.1Sb
4.05 3.33 3.31 3.60
4.09 3.32 3.17 3.55
~
'Scale r a n 9 was 1-5. Optimal w e o n me finttwa item was 5: onall other itemsthe optimal rare was 5. bp < 0.05. A nignlncarddmerencebetu- hlsset of -no was natedat the D < 0.05
IBYBI.
V < 0.01. SignlllcamdlWerencesbetween Wee painof meanswere notedatme p
