Arthur E. Grosser McGill University Montreal. Quebec H3A 2K6 Canada
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Film Segments for Chemistry Lecture Demonstrations these films t o he used by different lecturers, each of whom could penonalize it to his or her own style.
Demonstrations have long been a useful adjunct to the lecture. hut recent develonments have made their emnlovment more difficult. ~lassrbomsmay he so large that the f i i e details of a demonstration mav simolv be difficult to see. or classes may he held in lecture halls &"signed for non-sciehce uses and consequently are unequipped with lahoratory, or even sink facilities. In addition, such classrooms may he sufficiently distant from the chemistry lahoratory to make the transfer of chemicals and solutions cumbersome or difficult. Often of great importance are the costs of acquiring materials and manpower, and of preparing and repeating demonstrations each semester which may strain the departmental budget. Since all of these factors were present in the case of the General Chemistry course a t McGiU University, an alternative method or presenting demonstrations was developed: a 16 mm color film was oroduced comnrisine about 20 demonstrations e segments were projected of 3 min average duration. ~ h e s filk in the classroom a t the command of the lecturer who was free to provide his own description and interpretation of the experiments, since the film had no sound track.
Fllm Use The print, in which each segment was preceded by black leader and academy leader,2 was cut up into approximately 100-ft reels for portability. They were used in a course of 23 lectures. so on the averape. one was shown ner lecture to a class of 270 students in an aiditorium whose capacity is 550. The lecturer cued the nroiectionist hv turnine down the house lights; a t the end oie&h segment", the pr$ectionist cued up the next demonstration. Use in Other Formats
16 mm is a versatile medium since it can he transferred easily to other formats. For example, one of the filmed segments was used in a chemical kinetics class of 60 students. The filmed material was transferred via a tele-cine chain t o 3 1 ~in. videocassette in the Instructional Communications center control room. At the same time a sound track was added by the lecturer. The students viewed the 16 mm film in their classroom and could review the materialat one of three color video playback units available in the Chemistry Building.
Film Preparation Demonstrations were selected from this Journal and were reproduced in the laboratory prior to filming, which was done either in the general chemistry lahoratory or in a studio of the Instructional Communications Centre of M c ~ i lUniversity, l lt was quickly found that studio limitations in la~oratoryfa. cilities were more than compensated by the ability to control the background with photo studio colored seamless backdrop paper and by the presence of a sophisticated lighting control avatem. -,------Since the classroom had a projector-to-screen distance of 60 ft (screen size: 9 ft X 9 ft), it was decided to use 16 mm film. Most of the film shot was Ektachrome 7240, a direct reversal film, using an Eclair NPR 16l with a Angenieux 20:120 Zoom lens. When time-lapse photography was required, a Bolex H16 was emnloved. The Eclair is far easier to use since the viewfinder is very bright and the electricdrive permitsshtm as long as rewired I12 min with a 1OC-ft reel!. The develoned film was editeh on a Steenheck 4-plate editor and tapespliced. Of course, more modest equipment would have yielded, with a bit more inconvenience, equivalent results. 21 sements The edited film, of 62 min duration,. comvrised . with as many as 1 3 separate shots per segment. ( ~ 6 pere centage of film used in final footaze was 80%of that shot.) This film was cement-spliced and piinled at a commercial film prwessing laboratory. While the splices are visible under close examination with a film editor, they are not apparent during projection. The decisions affecting individual shots in each segment were governed by the principle that no person he shown recoenizahlv. In nractice. onlv the hands of the demonstrator &re visible. draphicsand iarge labels were used extensively so that the orocedures would he intellieihle even in the absence of the lecturer's live e x p l a n a t i o L ~ h i swas to enable
student R~~~~~~~~ T o ascertain the value of this experiment, the students were asked to record their reactions to the filmed demonstrations. The results (as percentages) are indicated in parentheses.
A. ~h~ moviesof the filmed demonstrationswer+. a. very welcome (91%) b. somewhat welcome ( 8%) e. somewhat unwelcome ( 1%) ( 0%) d. very unwelcome B. I found the filmed demonstration-my understanding of the subject matter. a. greatly helped (31%) b. helped somewhat (48%) (11%) c. hindered somewhat d. greatly hindered ( 0%) filmed demonstrations. C. I would suggest that there b+such a. many more (26%) (57%) h. a few more c. a few less (16%) d. many less ( 1%)
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This constitutes a very positive response, especially when viewed in the lieht - of the students' evaluation of other instructional elements. Costs Commercial 16 mm silent film nroduction costs are reckoned a t about $1500 (or more) per minute of finished film. By nroducine it "in-house" these costs can he cut drasticallv. For example,"the author's budget to produce 6U min oifinal fwkwe was $8000: 53XM for film stock and lab costsand 53000 for s"mmer salary tor an undergraduate laboratory assistant. Of course if a camera and film editor are not freelv availahle. cmts could have been $ 1 W 3 0 0 0 higher. For s m d classroom use, Super 8 film may he acceptable, reducing film stock and lab costs quite markedly. Commerciallyavailable instructional films hut i t is ~ of filmed ~ demonstrations, , ~~ are ~ ~another , l source difficult for the lecturer to personalize what is shown to his own style and editing of the film, even after purchase, is genVolume 57, Number 11, November 1980 / 795
erally illegal. Against this, one must balance the expenditures for preparing and presenting the same demonstrations year after year, or semester after semester. Conclusions
The author regards the use of filmed demonstrations as a useful device when the constraints mentioned at the beginning of this paper are important enough to eliminate demonstrations from the lecture. It should be stressed that someone on the production team should have a good eye for visual com-
796 1 Journal of ChemicalEducation
position and lighting. The technical expertise governing exposure values is learned easily, but the aesthetic judgment and the ability to tell the story in a cinematic sense using the full vocabulary of film possibilities is more difficult to master. Acknowledgmnt
The author wishes to thank Ian Ross for laboratory and production assistance, Chris Schon for preliminary filming, Mario DiPaolo for editing, and the Centre for Teaching and Learning for a grant to pursue this project.
