The Use and Evaluation of Videodiscs in the Chemistrylaboratory Arlene A. Russell University of California, Los Angeles, CA 90024 Mina G. Staskun The University of the Witwatersrand, South Africa Bernie L. Mitchell Officeof Instructional Development, UCLA, Los Angeles, CA 90024 The availahility of videodiscs presents a new, exciting opportunity for the educator to increase the efficiency and effectiveness of instruction. The videodisc goes back to 1928 when G. K. Baird first encoded a video signal onto a phonograph record ( I ) . I t took 50 years, however, for technology to catch up with his discovery and make the videodisc practical. Physically, a laser videodisc looks like a metalized, longolavine . . " record. The olastic disc contains 54.000 discrete frames or a~ncentricrings on which information can he stored. The information is encoded hv a series of de~ressionsoressed into the plastic surface, whiih is covered kith a highly reflective coatina. In order to olav . . a videodisc and retrieve the information stored im it, thr disc is spun at 1800 rpm while a r reflected off the surface. laser heam in the videudisc ~ l n v eis Because there is no physicai contact of a stylus with the disc, the surface is not worn by use. A variety of visual info-mation can be encoded on the disc. In its s i m ~ l e sform, t a linear oromam such as a film or videotape can be transfeired to adis;. One advantage of the videodisc for this kind of program is the increased durability of the disc over the tape or film. Still pictures can also he encoded on the disc. I t should be noted, however, that the quality of the imaee oreserved on the disc can he no better than that of the o r i g n i . The videodisc cannot enhance the quality of the image. Therefore, it is essential that all visual material he of as high a quality as possible. Theoretically, each of the 54,000 frames can be used for a ~icture.The archival value is obvious: all the works of art from the museums of the world could he stored on a few discs. Videodiscs can also contain a mixture of still and motion pictures. Motion pictures rapidly consume disc soace and . oromam time: still oictures do not. Thirtv still pictures (or frames) require the same disc space as one second of motion dcture. ~ d d i t i o nof a microprocessor to the videodisc player enhances the potential uses of videodiscs. The microprocessor rapidly accesses any of the 54,000 frames. Because each frame is unique, the "freeze-frame" capahility of the disc gives a high-quality still picture in marked contrast with videotape. Also, since the laser does not wear the disc; any single frame can remain on the television screen for an indefinite length of time. This is not the case with videotape which will selfdestruct. Videodiscs also have a substantial advantage over videotape in the time needed to locate any specific frame. Since the laser beam moves less than 4 in. across the radius of the disc, the scan takes only a few seconds. In contrast, locating a specific scene on videotape requires sophisticated equipment; and even then i t is a time-consuming procedure. At best, the time A preliminary version of this paper was presented at the 183rd National meeting of the American Chemical Society, Las Vegas. NV. April 1982.
420
Journal of Chemical Education
to scan a 30-min videotape program takes several minutes. For a videodisc program of this length the access time to any frame is under 3 s. The durability, high-quality picture, and rapid randomaccess capability of the videodisc can he further enhanced by the addition of an external computer. With this external computer, a designer can build into the program extensive branching and looping to various sequences of material. For examole. a student mav he given the choice of the level of difficult; of material to he studied, or the program can he designed to go automatically to material a t a level commensurate with a student's prior response to a question. Hiscox ( 2 )described the videodisc daver connected to an external computer as one of the few delivery systems currently conceived that is designed to handle large amounts of different material, vary its presentations in response to existing and developing student interests and abilities, measure student progress and provide feedback, and allow as much time as required for the student to learn a given concept. UCLA developed one of the first chemistry videodiscs. It was produced in 1981 and introduced into the freshman lahoratorv curriculum durine Winter Quarter 1982. In desienine " " this project we specifically developed a program that used the videodisc olaver's internal microorocessor. Two factors influenced t'his"decision. First, we'wanted a "user-friendly" svstem: second. we wanted a transferable Drogram. An extkrnal compute* would have detracted from this latter goal. Instead, any institution with a Pioneer videodisc player can use the videodisc program that we developed. All the programming information was placed directly on the disc so that ;he only hardware requirement is a videodisc player. Few studies evaluating videodisc programs have been reported (3-7); many emphasize the in&uctor's and student's ability to use the equipment and their attitude toward videodiscs. We descrihe one of the first quantitative evaluations of an interactive videodisc program. The specific program is concerned with a freshman thermochemistrv. exneriment in . whirh students measure the temperature deprndence ot'the soluhilitv ..nroduct of lrarl chloride IIV titratinn of chlmidr with silver nitrate using a Mohr titration.
-
Videodisc Program Deslgn Throuah - the use of student choices and branches to correct erroneous responses, the program allows each student to see material suited to individual needs. T o beain the oroaram a student selects either the entire program or any of its components-theory, experimental procedures, safety precautions, and quizzes. Figure 1 shows a schematic flowchart of these choices. Within the program, nine hranches (Figs. 2a, b) allow the student to bypass known material or view additional information on unfamiliar aspects of the experiment.
LN(c~). A n
I - AH -x-+con.tont 3R T
you familiar with the algebra to dsterrnlm the terms in
rw!red
this
Figure I.Flow chart of the videodisc program.
When a student gives an incorrect or negative response, the promam a i d e s the student throwh the relevant steps leading ;o the rorrect answer. If a student gives a correct or posittve response at a l~ranrhpclint, thr program continues and skips thiexplanatory loop.-~tthe end ofthe program, the student may take a quiz based on the material viewed. The quiz for the entire program contains nine multiplechoice questions. When the student gives a correct answer, the indicates that the answer iscorrect and then proceeds to the next question. When the student gives an incorrect answer..~ the nrogram indicates the error.. .. eives the correct ., answer, and then loops back into the section of the material in the nromam nrrtainine to the item thestudent missed. Onlv when 'this review is finkhed does the program present the student with the next question. After the last question the student is given the total quiz score.
~.
Viewing Procedure During Winter Quarter 1982,60 students voluntarily used the videodisc as part of their preparations for the experiment. They viewed the program in a small resource room near the freshman laboratories. Usually students viewed the program individually; when they worked in pairs they collaborated on responses to the program's questions. While students were viewing the program, we observed them and recorded on a standard form both their responses and their use of the videodisc player. Evaluation Our evaluation of the videodisc Droeram consisted of three parts: the responses students made w h e using the videodisc program, their videodisc quiz answers, and their lab performance. Students' Videodisc Responses
After the students had finished using thevideodisc we analyzed their responses to the program. Only one common feature emerged; on first viewing, all students chose to see the entire program. Within the program, the responses varied (Table 1).The theoretical section evoked diverse responses. For example, at the branch point shown in Figure 2b only 35% of the students responded "No" and watched the explanation. At another branch point dealing with theory, 88%of thestudents viewed the additional material. By contrast, on the
constant?
Figure 2.Examples of two branchgoimquestions Table 1. Vlewlng Chokes at Various Selected Branch Points Viewers
Non-viewers
A. Theoretical Material I Lcgarithrnic manipulations
35%
I1 Volumetric calculations 88% B. Experimental Procedures I Experimental temperatures 97 % I1 Precautions with AgNO3 65%
I
C. Data Analysis Features of welldrawn graphs 44 %
65% 12% 3%
15% 56%
"kr;n
%
10
0
4 SCORE 5 6 7 8 9
Figure 3. Student performance on the videodisc quiz.
branches concerned with experimental procedures most students asked for additional information. The third section of the videodisc . nroeram covers the data analvsis for " ~rocedures . the experiment. In this section, almost half the students sought additional instruction on graphing procedures. At the end of the program, 92% of the students elected to take the quiz to test their knowledge of the material (Fig. 3). These responses to the program suggest to us that even though the theory of calorimetry and basic techniques had been taught, not all students had mastered the techniques. A videodisc program such as ours can offer several levels of instruction including material that may he review for some Volume 62
Number 5
May 1965
421
students. We know students have varied backgrounds and instructional needs even for laboratory work. These results substantiate the advantages of interactive videodisc programs over traditional linear videotape programs. Videodisc Quiz Analysis In addition to our interest in students' requests for instruction. we were concerned with the effectiveness of the instruction they received from the videodisc. We compared the students' quiz answers with their requests for information a t the branch points within the program. We found that on the five quiz questions relating directly to a branch, most students who viewed the branch answered the quiz question correctly. Since the student's request for information a t a branch implied a need for instruction, we infer that acorrect quiz answer demonstrates successful instruction (Table 2). In the particular branch point shown in Figure 2b the explanatory material included a discussion of the expansion of log xy and log xa. Students were unaware of this. A quiz question dealt specifically with these logarithmic manipulations. We found that 65% of the students who viewed the branch answered the quiz question correctly (Table 2, Branch HI). Bv comnarison. onlv 50%of the students who did not view the branch Eorrectiy answered the related quiz question. Laboratory Performance Ultimatelv. the coal of the videodisc oromam was to Prepare students fo; the laboratory experimeht. T o measurethe effectiveness of the videodisc program we compared the laboratory performance of the videodisc users with the performance of a group of students who had viewed a videotape related to the experiment. We felt that student motivation and differences in lab instructors might affect our comparison. hlotivation was compensated for hy selecting only students u ho had n,lunlarily usril either the vidwdisc or the videotape. Each of our teaching assistants is responsible for two sections of the course. We offered the videodisc program to only one of each teaching assistant's sections; we selected the videotape users from the other section. We thus matched volunteer videodisc and videotaoe users with the same laboratorv instructor. Comparing thkse groups, we found that the videodisc users did significantly better on both a prelaboratory written class quiz and on experimental accuracy (Table 3). The eranhical analvsis of the data also showed a difference in favor of the videodisc users although the magnitude of this difference was not significant. Conclusion
There has long been speculation that videodiscs could fill a void in the instructional tools available to educators. Our prototype program confirms this expectation. The videodisc
Table 3.
Table 2.
Quiz Questions Relating to Branch Polnts in Program Quiz
Branch' Ib
Ill" IV' V'
8
100
0
92
65
14
92
80
8
100 65 50 51 100 93 100
20 0 35 50 49 0 7 0
40
60 95 4 92 8
is a valuable means to teach the varied student bodv now in colleges and universities throughout the country. s t u d e n t reaction t o our videodisc was unanimously enthusiastic, and led to many requests for interactive programs for other exneriments. Other subiects will also benefit from interactive, bidendisc programs. Acknowledgement
The authors gratefully acknowledge Lawrence Levine who prepared the videodisc computer program and Andrea Rich, Assistant Vice Chancellor, Office of Instructional Development who provided the financial support for the project. Literature Cited (1) B?auo,Ludwig,"Mi~meomp"teteandVideaDlseSyatems: MsgicLampforEducatoto?" 839. StateUniversityaf New York. Stony Brmk, 1971. ERIC Document
#154
(2) Hiseox, M. D.. "IntegratingTestingsnd lnstructionUaingthevideodisc:
~
~
~~
~
Comnarison of Videodisc and Videotaoe Users Videotape Viewers
no. of
mean
S.D.
students
mean
S.D.
students
1.50 41.5 4.57
1.60 0.03 1.19
58 57 49
0.96 39.1 4.17
1.15 0.03 1.34
54 55 53
One of slx questions on quiz. Maximum for mis question was 4 pains "tandard enthalpy in kJ. Maximumof 6 points
Journal of Chemical Education
1981.ERlC
ddisc: An InsVucfionalTool for the Hearing Impaired: 1980, 1200 227. y InteractivePrGectei .~theUnivusity dIom."WFEOCwnputing c & i uni,ity 01lows, m a u t y . 1980. (6) Bundemon. C. Victor, and others. "PrmEofHk~ceptDemonsVationand Compwative Evaluationof a Prototyp Intelligent Videodisc SrJfem. Final Report," 1983, ERIC
.~.
no. of
422
(%)
'Choice to uisw branch occunsd in main p r ~ r a m prior to quiz. "xperimental solubility paduct. R~cognition 01 relationshipbetween Kq and [Girl. dLqarithmic manipulations. Tempershlre range in experiment. ~VOiYmelriC CBiC~latiDnS.
Videodisc Users
Written quiz' Experimental accuracya Graphical analysisc
lncorren
(%I
Response ( % ) Correctly Answered Incorrectly Answered Viewers Nan-viewers Viewers Non~iewers Viewers Non-viewers Viewers Non~iewers
IN5
Carren
p p
< 0.05 < 0.05 N
