Daniel C. Pantaleo Floyd Junior College Rome, Georgia 30161
Videotapes for Laboratory Instruction in Freshman Chemistry
The freshman chemistry course a t Floyd Junior College consists of a two-quarter sequence. The laboratory in the first quarter has three objectives: (1) to demonstrate and supplement the lecture material, (2) to introduce the student to some of the basic equipment and techniques of chemistry, and (3) to have the student gain some skill in both the use of the equipment and the implementation of the techniques. The second quarter has a project oriented laboratory similar to that described by Lauren Wilson in this Journa1.l In this second quarter the student is directed to apply the skills attained in the first quarter in light of the analysis procedures which are obtained from library reference material. The objectives of the second-quarter lahoratory are: (1) to reinforce and augment laboratory technique, (2) to instruct the student in basic qualitative and quantitative techniques, and (3) to familiarize the student with library reference materials as related to chemistry. As is the case in most smaller colleges, particularly junior colleges, there is often a pronounced lack of qualified student assistants for helping with instruction and guidance during laboratory sessions. Consequently, the chemistry instructor is constantly searching for ways to prepare the chemistry students for a given session so that they may more efficiently spend their lahoratory time. Any methods developed should help in at least two ways: (1) eliminate or shorten in-lab instruction and (2) prevent interruption of a laboratory session with additional or forgotten instruction, thus breaking the continuity of the laboratory. We have recently purchased equipment for the production and viewing of video tapes and have found that the resulting locally produced tapes have helped in the above two ways. In addition, and perhaps more importantly, the retention by students of information normally presented as part of a pre-lab lecture has increased since implementation of these programs. In our library we have installed seven Panasonic 134x1. color television sets, Model CT-301, each equipped with a Panasonic %-in. videotape cartridge player. Each setup is equipped with one set of headphones, but is capable of supporting eight headsets. These units are located in study carrels (see the figure). One week before a given laboratory, students are assigned an appropriate tape to be viewed at least once previous to the day of the lab. The tapes are checked out a t the circulation desk where they are kept on reserve. Cartridges are easily inserted into the player units and can only be inserted one way. After the tape has played, the cartridge automatically rewinds and is rejected from the player. The tape cannot be removed while playing, hut can be rejected by moving it fast forward to the end of the program. The player units also have the capability that a student can rewind the tape to any position and replay any section of the tape or can pause during the program a t any given point by simply depressing a stop button. Initially, we have focused our attention on the first-
'Wilson, Lauren R., J. CHEM. EDUC., 46,447 (1969). 112
/ Journal of Chemical Education
Avidemape carrel
quarter laboratories and have produced the tapes listed in Table 1. Tapes 1, 2, and 3 present material usually covered during the first laboratory period. Thus one complete laboratory session has been freed which allows introduction of another experiment into the lahoratory sequence. In developing tapes for specific laboratories, we decided to pinpoint (by student survey) those labs which students found most difficult to perform after a normal pre-lab lecture. The results of the survev indicated that a series of three titration experiments fit this category. These experiments are: (1) ore~aration of acid and hase solutions and . titration of acid versus hase, (2) standardization of a base against KHP, and (3) determination of percent acid in an unknown sample. To date tapes 4 and 5 in Table 1 have been developed in response to the need. Both these tapes use equipment actually used by the students. We have observed that those classes using the tapes in Table 1 are able to operate balances much more smoothly and titrate much more precisely than those exposed to the Table 1. Initial Programs Locallv Produced 1. Scientific Notation and the Slide Rule: 20 min-Black and White Demonstrates the use of the C and D scales for multiplication and division. Simple problem lead to more complicated ones, introducing scientific notation. Problems are presented on the screen, using a character generator. Problems were done on an ordinary blackboard in an earlier tape with no
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2. Principles of Weighiig-The
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Ohms Disl-O-Gram and Mettler P-162-
Demonstrates the mass "balance" principle by showing the l ~ s e of a simple two beam dial balance. Reading a vernier is explained using the dial-o-gram balance. Similarly, the principles of using s top-loading type balance such as checking Level, zeroing, and weighing are presented. 3. The Mettler H-lo Analytical Balance Use and Care Operational procedures and care for the balance are demonstrated through the weighing of an object. Split screen views of the weight knobs and the wehht whdow are "srrl thr"ur1,""l. 4. Titration of an Acid Againit a Base The preparation of approximately 0.1 M HCI and NaOH solutions are demonstrated. Cleaning and rinsing of equipment as well as reading the meniscus are ahown. An actual titration is run and the equipment is cleaned and prepared for a second titration. An explanation of the eslculation and criteria for acceptable work (3 ppt) end the tape. 5. Sbndardization of a Base Against KHP The previously prepared base sololution is titrsted against KHP. Three samplesof KHP are weighed out on an analytical bhlance. One of these is repared for titration and is titrated. The apparatus ie cleaned and prepared for a second titration. Again calculation and precision criterion end the t a w .
normal pre-lab instructions. More concretely, in those classes using the tapes 90% of the students met the crierion for acceptable work (3 ppt precision) in the first 3-hr .lab period, while those students who were not exposed to the tapes had 75% success in attaining acceptable performance in the first lab period. Also, a short lab quiz (15 min) is given prior to each lab over the material covered in the lahoratory manual. It is found that the average grade for these quizzes for those students using tapes is 86/100, while scores on these quizzes before the use of tapes was averaging 73/100. The success of the videotapes probably lies in two factors. First, proper planning of a tape, including script outline and equipment setup, results in a program which is thorough in covering all important points. No matter how well prepared a pre-lab lecture is, often a point is omitted which causes student errors or necessitates interruption of the lahoratory. This problem is circumvented with videotapes for if some point is missed in planning, it is caught during the actual running of the experiment for the tape. Production time for a 15-20-min tape may run from 1-1.5 hr. Upon completion, however, a source of pre-lab instruction is obtained which is always uniform in its coverage of the important points of an experiment. The second reason for the success of the tapes is that the student may view these tapes for review or to refresh his technique several times before (or even during) a lahoratory session, whereas he can listen to a pre-lab lecture only once. In addition, each time he views the tape he receives a uniform, complete presentation. The preparation of the tapes was a two-person operation. As chemistry instructor, I prepared the scriptoutline and equipment setup, as well as indicating what key features or desired camera angles needed to he shown (e.g., closeup of reading a meniscus). Our audio-visual technician then set up the cameras and any effects that would he needed. Then, hy following the script outline he controlled the camera selection and effects, such as split screen views. from the video console. We have found that recording the audio during the actual taping is preferable to dubhinc the sound onto the taDe later. The eaui~ment. .. however, does allow dubbing if a n error is made in the narration during the course of recording the tape. The production of tapes has been surprisingly simple and free of any major difficulties. Table 2 lists the equipment we have used for the production and viewing of videotapes. The cost of the black and white and color equipment is $35,562. Deleting the optional color equipment, the cost drops to $14,294. Initial titration tapes were done in black and white with a shade change visible a t the endpoint. The color tapes serve to make the situation a little more realistic, although the students need more to observe the technique than the color change a t endpoint. Mention should also be made of the relative costs for other audio-visual methods. This past year our mathematics department equipped a mathematics audio-visual lahoratory for use with a self-paced college algebra course. This lab centered around synchronous slide projectors and tape cassettes. The equipment making up this lab is listed in Table 3. The total cost of this equipment was $12,800, approximately the same cost as a black and white videotape setup. Perhaps more important a factor is that the time needed to prepare a 20min slide cassette program ranges from 20-25 hr excluding the time needed for processing the film. A videotape pro-
Table 2. Equipment Needed for Videota~eProsrams Item .. . nlnek and White T.V. camera. WV-3m,H S - 1 4 ~ h. 14.70mm. f 2.0. Zoom l c n s. 2:l.. interlace board, 550 I& hotii. resolution Black and White T.V. camera WV-240P. 8.5 mm A 5. ~~
~~
~~
Appmr. cast
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Swiuhar Fader, conmle monitor,
V Y 922 S t.' Admlrnl Educator T.V. Momtor Model 3E7R6 Hllhky, QIIII
k .XI T n p d
Mcruohmae EV-WI MC-125 Microphone Mixer; M-68Shure Panasonic VTR Editor NV-3130 Panasonie CT-301 13-in. color T.V. Cartridge Players. NV-5120 BASF '/*.in. . Videotam 2400 ft: 1hr duration Kit for preparing 24 cartridges Black and White Sub Total Studio Color Camera controls WV-2100P/WV-S200P ~
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Color Synchronizing Generator WJ-1KMP Sub-carrier Phase Shifter Distribution Amplifier 0°-
350°C-WJ-1700P
Color Speeial Effect. Generator WJ-5000 P Intercom end Extension cables for camera 600HP23A-25 Television Control Monitor TN-633 Color Receiver Monitor 13-in. CT-25 Triwd and Dolly Quick Set 7301/7601/7230
Stvdio mntml console junction boa WJ-9WP Wireless microphone and receiver. Mixon lapel microphone and hand held microphone DM-I/ PM-3/STM-Y 4 channel recording microphone Lighting system (7 lighte) T.V. character generator 0-1032 Color Sub Total Grand Total
Table 3. Equipment and Supplies for a Thirteen Unit Audio-Visual Laboratory Q~antit"
Item
m-mi" tape cassettes Kodak Kodaehroms Film Slide trays Blank t a p cassettes Carrel units (Carrel slide projector optical t r a k and cassette player 35mm Camera Slide duplicating apparatus Total Cost: 612.800
gram of the same length takes, as noted before, from 1-1.5 hr to produce with the program ready to be viewed a t the end of this time. In addition, synchronization has been a problem with the slidetape setup, particularly when a program is run fast forward or is reset to some point in the narrative. The videotape process has no such problem since the sound is on the videotape. We plan further use of videotapes for instruction in both equipment use and lahoratory technique. Additionally, instructional tapes on the metric system and gas law problems are also planned. In conclusion, we have found that videotapes as instructional aids are comparable in cost and require less production time than standard slidetape programs. Perhaps most importantly, this audio-visual technique is demonstrably beneficial to the chemistry student. Acknowledgment
Grateful appreciation is expressed to Mr. Charles Brown, Audio Visual Technician a t Floyd Junior College. Also acknowledged is Grant No. 04-H-000425-01-0 from The Appalachian Regional Commission used for purchase of videotape equipment.
Volume 52, Number 2, February 1975
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