Clifton E. Meloan Kansas State University Manhattan, Kansas 66502
The Use of Tape Recorders, Films, and Real Samples in Laboratories
During the past year we have experimented with a technique for teaching chemistry laboratories that has had amazing success. In summary, it consists of putting the directions on a cassette tape recorder, putting techniques that are difficult to exdain or comm& to several experiments on a short ( 2 3 k i n ) cartridged film loop with a sound track; and using a real samule as the focal noint of the exnerimnnt. We have found the following advaitages 1 ) Sttldmr i n w ~ c ~hss y in,reased almmt imhelievnbly. Severxl itwimr.. did cvrra experirwnL3 dtrriv.~final week and after rhr mnr\rrr endrd. The m r u r e uf the iurnples 1% the mnitr reason. 2) The professor and assistants were more avdable to answer questions during the labomtory period. 3) More information was transferred because full explanations could be given s t the moment of the operatiop, and the students seemed to remember it better this way. 4) Individusl instruction by tape by the professor could be given to each student. 5) Techniques, which are often demonstrated incorrectly by graduate assistants, are shown correctly in the films. 6) More complex equipment can be used making the experiment moie realistic. The student is talked through the use of the equipment, which is hard to do by written directions. 7) All students get the same explanation, which is particularly important in instrumental analysis where it may be several weeks between the first and last students who do the experiment. 8) The students can work at their own pace. Directions can be replayed and film reshown as needed. This is not completely "cookbuok," because each student's sample is different. 9) Less laboratory space is required because equipment can be used repeatedly, not as many items are needed, and the lab can be scheduled to a fuller capacity.
Disadvantages 1) The large amount of time spent on setting up the initial experiments. 2) The cost of buying the chemicals and equipment required for the new experiments. Much of this can be amortized over several yems, however. 3) The time spent convincing some faculty that tt will work.
How It Works
This technique has been tried in two classes, Chemical Separations and Instrumental Analysis. Chemical Separations is a sophomore course for -chemistry and biochemistry undergraduates, plus a few agriculture graduate students. Our Instrumental Analysis class has 38 students this semester (18 chemistry majors, 6 biochemistry, 1 chemical engineer, 'and 13 graduate students). Thirty-one separation experiments were set up (see "Experiments" section below), and the student was to pick any fifteen based on his experience and major area. Twenty experiments were set up for Instrumental Analysis with the student picking twelve based on his individual requirements. The student is not expected to come to class "cold."
He is given a few sheets of information consisting of the following which might be combined into a lab manual in the future. 1) The equipment needed and the chemicals required. (This is primarily for use by the assistants so they can set up the experiment, but it also serves as a check list for the student.) 2 ) A brief sketch of the apparatus set up. This is so the student can identify the equipment and also so the equipment can be set up i n the future to match the tape. 3) General ProoedureA paragraph or two giving the overall picture of what will be required. This is not detailed enough for the student to do the experiment, but serves two main purposes, (a) as a refersher for the instructor and (b) lets the studentknow if there are any long delays such as a 2-br. electrophoresis develop ment. The student can plan on this and not waste time. 4) General Infarmrttion-This gives the chemistry of the sample being investigated, why it is important, the reactions involved, literature references, and example calculations.
The shortest of these has been 3 pages, the longest 6 pages. A sign-up sheet is posted and the students indicate which experiment they want to do and when. This insures that two students do not show up expecting to do the same experiment and that the assistants will know what reagents to check. When the student arrives, he gets a tape recorder and the cassette containing the instructions. The tape contains a few jntroductory remarks which can be changed each year to keep the tape current. Each item of equipment is then explained. Bits of masking tape placed on the apparatus and numbered with amagic marker serve as a way to direct the student's attention to a particular area. Certain techniques, such as injecting a sample into a gas chromatograph, are almost impossible to explain on tape. The student is then referred to a film. These are short, 23-min., cartriged films with a sound track. After the student sees the film, he practices it a few times and then turns the tape recorder hack on. After all of the apparatus has been explained and the manipulative techniques practiced, the actual experiment is started. During the 'explanation, two wmmandg are used-Stop and Stop-Start. Stop is used after the student has been directed to do something. This is so he will stop the. tape recorder. The command, Stop-Start, is used when there is a long waiting period that shouldn't he wasted. For example, if the student is directed to evaporate 200 ml of solvent, he is given the command, Stop-Start. The student will stop the tape recorder whiie he puts the container on the hot plate, but will then start the recorder again to get the next set of directions. Some Observalions
Tape Recordis. We started out with the same type used by biology classes in carrells. These did not work Volume 48, Number 2, February 1971
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because too much motion is required in a chemistry laboratory, and they were too big. We are currently using the Sony TC 110, which is a transistorized, cassette type. This is light enough so that the student can carry it over his shoulder or around his waist. We use ear plugs rather than ear phones because they aren't as hot and most students are used to them because of transistor radios. For health reasons, the student buys his own ear plug. We are going to try "playback only" units since no recording is necessary by the student and the units are much cheaper. This will reduce the cost to about $2530 per unit. Ninety-minute cassettes have been found to be the hest. That will provide for a 6-hr lab if necessary. Few experiments require longer time, and 11-e have had trouble with 2 hr cassettes jamming due to the continuous starting, stopping, and rewinding, We find that the initial tape has many grammatical and scientific errors in it. Making a script first was found to require an unbelievable amount of time. We type this tape, and add any revisions based on student comments. A second tape is then made. It is very hard to make this tape as spontaneous as the original. Samples. This has been a real problem. It is easy to use the same kinds of sample repeatedly. We have tried to have a wide variety of samples, each one requiring a different handling technique and d i e r e n t chemistry. Most of the methods are official methods used in industry, on a routine basis, so we know they will generally give good results even for beginners. The guideline has been the ACS list of divisions. It is felt that if there is enough chemistry in an area so that the ACS has a division for it, then that area ought to be represented in our samples. We also try to use samples that the student comes in contact with daily. See section on Experiments for examples of this. Films. We made our own using a Bolex Super 8 camera with a zoom lens. They are not perfect but they do get the idea across and the total cost is about $30 each, not counting our labor. Silent films were a failure. The sound films are quite popular. We use a Fairchild Mark IV-S to show them. By keeping them to less than 3 min, and shooting in sequence, there are no splices which cause problems, and if a student misses a point he is only 3 min from seeing i t again.
Elution Column Chromatography: Noseapine and Phenirm i n e in Cough Syrups Gas Ch:hromatography: BHA and BHT Antioxidants in Cereals Paper Chromatography: Tri-Sulfa Drug Tablets Thin Layer Chromatography: Nine Antihistamines in Capsules and Tablets Dise Electrophoresis: Amino Acids in Fish Horizontal Strip Electrophoresis: LDH Iso-Enzymes in Blood Ion Exchange: Cl-, Br-, I- in Brine Waters Ligand Ezchange: N2Ht, CHnN2H8, and (CNn)2NgI& in Rocket Fuels Gel Permeation: Vitamin BL1from Dextrans Dialysis: Phosphatase in Milk Masking Agents: Zp in Rubber Gas Ahsortption: COz, Nz, 0 %CO . in Car Exhaust. Plotation: (a) Fly Eggs and Maggots in Canned Tomatoes (b) Insect Fragments and Rodent Hairs in Flour Electroplating: Cu and Ni in a Nickel Microbiological: E. Coli in Waste Water Ion Retardation: Salt from Serum Sugars Thamal Diffusion: Hz from Nz New Topics To Be Added Ring Oven Liquid Chromatography Gradient Elution Zone Refming Foam Fractionation Agar Diffusion Dye Transfer Immuno Electrophoresis Instrument01 Analysis
Visible-Ultraviolet: Detergents in Sewage and River Water Infrared: (a) Fibers and Fabrics by MIR; (b) Propellants in Pressurized Containers Fluoresceme: Vitamin C in Fruit Juices Flame Photometry: P i n Bones Atomic Absorption: Ce. in Urine Emission Spectroscopy: An Aircraft Alloy Gas Chromatography: BHA and BHT Antioxidants in Cereals Turhidimelry: Papain in Beer Light Scattering: Particle Size in Soaps Refmetometry: Fat in Canned Mests Polarimetry: Starch in Corn and Wheat Dise Electrophoresis: Amino Acids in Fish Horizontal Stnp Electrophoresis: LDH Iso Enzymes in Blood Potentwmetry: Nicotine in Tobacco Cmclometry: As in Glass Oscillometry: Fluoride in Toothpaste Polamgraphy: (a) Zn in Athletes Foot Powder; (b) Pipermine in Medicated Feeds Cycle Voltammetry: Epinephrine in Tranquilizers Conduetiuity: Milk Adulteration
Experiments Chemical Separations 1. Volatilization: COz in 2. Azeotropic Distillatial 3. Eztraclive Distillation: 4. Molecular Distillalion:
5. 6.
7. 8. 9. 10. 11. 12.
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Limestone Prep. of Absolute Ethanol Benzene from Cyclohexane Vitamin E in Lard Vacuum Distillation: Bensaldehyde from N,N-Dimethylformamide Entrainer Sublimation: Caffeine from Coffee Immiscible Solvents Distillation: Water in Fruits, Vegetables, and Meats Craig Counter Current Extraction: Fe, Co, Ni Sozhlet Extraction: Pyrogallol in Hair Dyes Continuous Extraction-Soluent Heavier: Caffeine in Cola. Drinks Continuous Eztraction-Solvent Lighter: Ipemc Alkaloids in Expectorants Displacement Column Chromatography: Cis-Trans Aaobenzene in Dyes
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Journol of Chemical Educotion
Outlook for the Future
We feel that to simply apply this technique to our regular laboratory experiments would be wasting its potential. Most students taking chemistry courses dislii
