Organic chemistry by distance learning.
Organic chemistry is not static. Textbooks can show mechanisms, but what could substitute for the instructor showing on a model, how the nucleophile attacks from the rear in an (S.sub.n)2 reaction or erasing a lone pair on the blackboard and clalking in a bond pair in its place as you explain the finer points of 'electron pushing'. The internal plane of symmetry in a meso compound is not always obvious to the beginning organic student when he or she looks at an illustration in a textbook or even at a model. But once the instructor holds the model in the right way and points out the plane, again probably with some hand waving, the student usually understands. Although drawing Newman projection formulas may seem very obvious once you know how, I find that students often have a great deal of difficulty knowing what they are supposed to do, even though I have discussed it in the lecture and, even though this topic is very clearly explained in the text. But on a one-to-one basis, if I take a model and line up the relevant bond with the student's eye and then I rotate the model through the staggered and eclipsed forms, the response invariably is "I get it now". How do you supply this face-to-face explanation through a correspondence course?
British Columbia's Open University (a division of BC's Open Learning Agency) has a team format for course development and the team decided that organic chemistry lent itself to a multimedia approach. Not only would the course have the standard components (a course manual, course units, an answer key to the practice exercises, an assignment file, textbook and a telephone tutor service), but there would also be an audio tape, a video tape and a model kit to be used as integral parts of the course (see Figure 1). The course director was Karel Baresch, an Open University media specialist. The rest of the team, on contract to the Open University, consisted of David Dolphin, FCIC, from The Department of Chemistry at the University of British Columbia, as course consultant, Francis Chow as editor and myself, as course writer. The role of the course consultant was to ensure the course content was accurate, up-to-date and appropriate. Dolphin reviewed the material at the first draft stage and we would debate changes, additions or eliminations over the phone. As well as the usual editorial functions of style and consistency, the editor served the valuable function of complaining when a point was not perfectly clear. If Chow, a biochemist, asked what something meant, then I had to assume the students would not understand at all. After his careful editing, I would review the material again to make sure any changes had not altered the chemical meaning. After a marathon phone session, we would produce a final draft that then went to the Open University for production.
Two-semester courses were produced, corresponding to a one-year course at the second-year level. These courses were not designed for an honours' degree in chemistry, but as a standard organic chemistry course for students majoring in areas such as biology, agriculture, forestry, dentistry, medicine, etc. However, my feeling is that a student, who passes these courses with a good grade, would easily be able to handle a third-year organic chemistry course. Although some topics are not covered in detail, the approach is rigorous and students are expected to develop understanding and the ability to apply what they learn. Each course has six units. Chem 240 unit titles are: Chemical Bonds and Carbon Compounds', Stereochemistry" Mechanisms of Organic Reactions','Alkenes and Alkynes', 'Alcohols and Ethers', and Spectroscopy of Organic Compounds'. The titles in Chem 241 are: Aromatic Compounds', 'Aldehydes and Ketones', Carboxylic Acids and Their Derivatives', 'Organic Nitrogen Compounds', 'Enolate Ions and Their Reactions', and Carbohydrates'.
The right choice of textbook for the course was very important as this is a'wrap-around'course. The units work through the textbook and it is crucial that the textbook be readable and understandable. I wanted to find a textbook somewhere between the large organic texts, which now seem to run to about 1200 pages, and the one-semester text of around 500 pages. While it is reasonable in a traditional class to leave out sections and chapters of the text, it is difficult for a distance-education student to cope with constantly being told to omit this and only do part of that. The one-semester texts did not seem to be complete and would have required a lot of supplementing within the units. Fundamentals of Organic Chemistry by T.W. Graham Solomons, (Wiley, 2nd edition) at 894 pages seemed to fit our requirements. The order of topics was appropriate and the material could be made to fit the six units per course format.
Textbook choice becomes even more important when you realise that you can't change the text next year if you are not happy with it. The Open University purchased about a three years' supply of the textbook, and so the 2nd edition will be used despite the recent publication of a 3rd edition. As I worked through the textbook while writing the units, I was increasingly happy with our choice. It is a good readable textbook; it is rigorous without being pedantic, and; the examples clearly demonstrate the main points. There is a comprehensive student study guide with fully worked out answers to all the problem sets.
The course units are central to the course and are what the student uses to work through the course. The unit size varies between 30 and 50 pages, depending on the amount of material in the units. Two or three of the units in each course are designed for three weeks and the rest are two week units. The course should take about 13 or 14 weeks and the final week or so, for a 15-week semester, would be review and the final exam. Each unit starts with a list of about 10 objectives the student should be able to accomplish after studying the unit, then an overview of the material in the unit and detailed instructions on what to study from the textbook. The unit is written in an informal style. The student is addressed directly as shown in the following example.
Confirm this sequence for yourself by applying the three rules I have just discussed. Then work on the following example and compare your answer to the one I give.' Each unit contains worked examples, a set of practice exercises and suggested supplementary exercises from the textbook.
Throughout the units, there are a number of margin symbols indicating what the student should be doing. As shown in Figure 2, these instructions are for reading sections of the textbook, working through problems, using the model kit to build a model, listening to the audio tape, viewing the video tape, studying the material and reviewing previous material. We used audio tapes for a specific purpose. Where a topic is in the text is fairly complicated, the audio tape helps the student with the concept. This is done by asking the student to look at a mechanism, or a graph or an example on a particular page and then explaining the material as they are looking. Some students may want to read the text explanation first, others may find it helpful to listen to the relevant portion of the tape first. Students are not expected to make notes from the tape. It is not a lecture but an aid to understanding. I am not the 'voice' on the audio tapes as the Open University has a policy against accents on their tapes. The course director originally thought that a professional voice would be the best choice, but one look at the script we prepared (lithium tri-tert-butoxyaluminum hydride, pyridinium chlorochromate etc.) changed his mind. So I was asked to recruit a chemist for the job and Bob Browne from Douglas College has done an excellent job on these audio tapes. I was present at the recording sessions at the Open Learning Agency studios and told Browne that you would never know that he was a physical chemist and not an organic chemist. I don't know that he took this as the compliment that I intended it to be ! The video tape was another story. Evidently the Open University has no policy against accents on video tapes and I was persuaded that I should be the presenter. The five days we spent shooting at BC's Knowledge Network studios and on location, were the hardest days' work I have ever done. Although we had made a preview tape with a hand-held video camera, revised, cut, reviewed, cut and edited the script many times, there were still problems once we involved three cameramen, a floor director, a producer, lighting and sound specialists etc.
The main aim of the video was to demonstrate those ideas I felt would be most difficult for a distance-education student to grasp. The video has very little of what could be called lecturing, but involves demonstrations with models, diagrams, spectrometers (uv/visible, IR and NMR) and simple test-tubes tests. Central to all of this is the computer graphics developed for the video. The sequences often involve a model, dissolving from the model to a computer image of the model where movement is possible and then back to a model of the product. The (S.sub.N)2 mechanism showing a Walden Inversion worked really well. So did the segment on stereospecific additions to cis- and trans-2-butene through a bromonium ion intermediate, which can be very difficult for a student to understand. But watching the mechanism unfold on the screen seems to simplify what is happening.
The first attempts at this modelling produced images that looked like worms coming out of apples. Jeff Leese, the computer expert, hired by the Open University to translate the images that I had in my mind into animation, was very patient as I explained about electron clouds and atomic orbital overlap. He eventually produced sequences where bonds break and bonds form in a credible way. By now we had sunk so much time and effort into the video, that it was decided we should really try for a wider market than just the distance education students in BC. And so, the final 60-minute video does not refer to the Chem 240 course and is being marketed independently together with a Concepts in Organic Chemistry booklet describing the 18 segments and gives practice problems for each segment. There is no video for the Chem 241 course. The topics that are most difficult for beginning students to visualize (stereochemistry, conformational analysis, nucleophilic substitutions, spectroscopy) are covered in the video for the first course.
This semester I am using the video as part of my organic chemistry class at Capilano College. I felt a bit awkward playing a video of myself to the class, but advised them to ignore the presenter and to concentrate on the models and computer animations. As each sequence is only about three minutes long, I wanted to see if running the animation at the appropriate place during the lecture was useful even in a traditional face-to-face class. For some sequences it has been very useful. I spent much less time explaining how an (S.sub.N)2 reaction involves an inversion. I didn't have to invoke the usual metaphors of umbrellas blowing inside out and I did much less hand waving than usual. And much to my surprise, numerous students have borrowed the video tape overnight or for the weekend, and many of them have said that the animations really help them to visualize what is happening. Chem 240 and 241 do not have a laboratory component. The complimentary laboratory courses, Chem 245 and 246, will be run in the usual Open University manner through the community colleges in the province, Capilano College will run its organic laboratory for the Open University students on three weekends through out the semester. Although each community college does somewhat different experiments in their own laboratory, each college has transfer credit to the universities for these courses. This procedure has worked well for first-year laboratories in chemistry, biology and physics and seven different colleges are now running Open University weekend laboratories.
Chem 240 was offered for the first time in March 1990. There is continuous entry to Open University courses so student numbers at any one time can vary. So far about 24 students have entered Chem 240. If you would like further details on how this or other science distance-education courses are offered, or on the telephone tutorial system, or if you would like details on obtaining the written materials, the audio or video tapes, you should contact Louis Giguere, Coordinator of Science Programmes, Open University of BC, 7671 Alderbridge Way, Richmond, BC V6X 1Z9. If you would like to know about the contents or development of the course (or such important facts as how to hold a model of 1,2-dimethylcyclohexane so that the it does not cause an annoying glint from the camera lights), I can be contacted at the Chemistry Department, Capilano College, 2055 Purcell Way, North Vancouver, BC V7R 3J5.
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|Title Annotation:||university level organic chemistry by correspondence|
|Publication:||Canadian Chemical News|
|Date:||Mar 1, 1991|
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