"Technique" can he separated from prohlem-solving, hut thev're eraded toeether when we grade products. In the area of &chnIque, lab is like cooking, drivLg, or playing tennis. I don't think this is had. Thev are all activities where the mind and body act together to convert ohservations into actions, sometimes unconsciously. I often try to overcome lab anxiety by asking a student what she likes to do and then saying "Oh, you'll enjoy organic lab and he good at i t i t must have a lot in common with hang-gliding." There is a further important area explored in depth in the organic lab-the philoiophy of keeping a record in a notebook. Because of the size of the classes and the quantitative natureof the experiments, I helieve many large schools don't emphasize the notebook in freshman lab. It's not even notebook-keeping as a skill, which we may take for granted hut has to be taught, so much as its importance we are teaching. We can motivate our student8 hy giving experiments long and complicated enough to make a good written lab record appreciated. A singleexperiment with multiple trialsw find an appropriate crystallization solvent will make a convert. (We expect and tolerate some backslidine.) When we teach the notebook as a lab record instead of a G v e n i e n t place to write UD reports. we can also show the difference between an ohservitioi and'a conclusiou. We thus address the objection you had to "teaching lab experiments to 'illustrate' a me-
Chemist II:
chanism." Observations stand; make new ones if necessary, hut don't expurgate. Feel free to change conclusions, among which may he the worth of certain ohservations. I agree with you: "Let the student think about procedure in lab and theory after lab." What we have to do is insist on a good record in lab and thoughtful written conclusions at a later time.~.~ on a r e w r t or auiz. Actually. Pickering, experiments with unknowns are popular in oreanic lab. At the end of the course. identifvine an unknown-from its physical, chemical, and spect&&pic properties gives students the sense that they have acquired enormous power to solve a problem. However, the questions that thev are asking themselves as thev work are the sameas those appropriate in extraction, synthesis, and purification experiments: What is this stuff? Is it pure? What's going on here? What should I do now? From ~traiehtforwardsindepurpose experiments, the students have gained experience examining their prejudices and thinking on their feet. Major reasons for the popularity of unknowns among teachers are how easy the grading is and how easily students are convinced of its fairness. If we want to, we can grade other aspects of lab ~erformancebesides ohtainina- the riaht - or wrong answer, and we can convince students of our ahility to doso. Then thev miaht he ahle to appreciate the intellectual content of a cr&.aliization experih;ent as representing an important aspect of our discipline. ~
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". . . an equilibrium between theoretical and practical aspects of organic chemistry should be established."
Raphael lkan The Hebrew University of Jerusalem, Jerusalem 91904, Israel
I have read with interest the personal reflections of Miles Pickering entitled: "A Physical Chemist Looks at Organic Chemistry Lab" (J.Chem. Educ. 1988,65,143). He certainly provoked me to reply to some of the ideas put forward in that article. It was indeed a pleasure to read that a physical chemist had the guts and the courage to venture into the world of an organic chemistry laboratory with five students and a black caiinstead of having a good time b y theseashore. I have been wondering about the origin of the black cat's name "Steroid". In mv opinion it mieht be the late L. Fieser's (from Harvard university) symbol of Siamese cats, Daae which he ~0SsesSedand which he used on the front . - of his p o p u l ~honks on steroids and natural products.. . . I should like to inform I'ickering that during his lapse of two decades from organic chemistry, it has undergone revolutionarv changes in various aspects of this science. Pickering clai& that "The lab is not a good way to illustrate abstractions. .".The organic chemistry lab and the modern organic chemist now uses ~ r ~ a n + ~ h ~ techniques &al such as 'H,IZC nuclear magnetic resonance spectroscopic, mass spectrometric, X-ray, and electron microscopic methods ( 1 J. Thus, today, minute quantities are sufficient for G U M S techniques to reveal the constituents of natural products. For example, 700 different organic compounds were detected in oil of coffee and 800 in beer. Another fact stressed by Pickering was "Our lahs show what oraanic chemists do with their fingers, hut not what they dowith their hrains.. .".This approach might fit every lah work that involves, of course, some practical dirty. finger. work. The students are now requested by their instructors to understand the theoretical background of the practical work. Furthermore, a series of experiments on an advanced level have been, and still are, being introduced into the organic chemistry lahs. These include various interdisciplinary fields such as, for example, natural product chemistry
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(2),biochemistry, and geochemistry. The students are also asked to design series of experiments as synthetically feasible routes to certain products. The student would have to give considerable thought and would involve literatwe and patent searches. Kozma (3)has shown that the recipes lab is preferred by students. However, in our organic lab (for chemists, biologists, as well as the medicinal scientists) we have waived the lahel of cookiue from the lah, since the students have to pass a brief examinvolving theoretical and practical aspects of the particular area of the lab suhiert iollowed h y a 3040-mindiscussion. After the lab workthe students are reassembled to discuss further the results of their practical work. The compromise of "let the student think about procedure in the lab and theory after the lab" contradicts our experience in teaching practical organic chemistry, which supports a "sandwich" approach, that is, theory-lab-theory. Thus the lab work is "sandwiched" between two theory lessons and a discussion. Our grading system is focused principally on the understanding of the subject matter. Overemphasizing the theoretical aspects and minimizing the practical work may lead to a situation where a student will he an expert on drawing mechanistic arrows of reaction pathways and not heing ahle to perform effectively the practical work in the lab. The conclusion is that an "equilibrium" between the theoretical and practical aspect8 of organic chemistry should he estahlished. The claim of "why not keep the identity of the white powder unknown" d& not ex& in our lahssince the isolation and identification of unknowns is as integral part of the analytical organic chemistry lab experiments. It is proposed that a micro-, semimicro-, and macroscale of organic practical experiments involving purification and separation techniques together with modern and tandem spectroscopic Volume 66
Number 4
April 1989
323
