tion of laboratory apparatus. This limitation is easily overcome, however, by utilizing videocassette or videodisk material on the same monitor as an integral .. nart . of the comoutercontrolled tuhrinl program. This terhnique permits t he disnlav" of "live" action wh1:n nwded in the lesson, inrludinr repeat viewing of the appropriate scenes as determined by&dent responses to questions in the program. Table 3 suggests some of the kinds of tutorial programs in which interactive comnuter nrogramming combined with video illustrations can be mostkff&tive. ~ r o m the standpoint of soeed of access and volume of video material available, it is ciear that videodisk offers the greatest potential. There is no reason, however, why any instructor should hesitate to develop video material &itable for his or her needs and to utilize it in tutorial programming via videocassette until the costs for videodisk production become more realistic.
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Exploring Chemistry's Mathematical Models with Computer Simulations John W. Moore Eastern Michigan Un~verslty Ypsilanti. MI 48197
In manv cases what I call "instructional simulations" can provide a new pedagogic approach to teaching chemistry. Such simulations can place students in a role similar t o that of a I sign~firesearch chemist, rt:quiring the student ~ I furmulntr rant questims, design appropriate simulated experiments, and internret intellken& the data obtained from such ex.~ - - ~ ~ ~ ~ periments. At the same time the computer can provide a set of tools for dealine with exoerimental data (ex.. software for plotting or transforming data) that compresses time, bringing the satisfaction of successfullv ~ r o h i n enature's secrets much more quickly than is usual in real l i f l Curiosity and disciplined inauirv can be rewarded ranidlv. and students are afforded tce opportunity to play with o&models of how nature works, thereby discovering implications of the models that even experienced chemists may not he aware of. The student user of an instructional simulation is able t o interact with a mathematical model through the medium of a computer. The student chooses parameters and the computer responds by calculating results on the basis of model
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Table 3.
chemistlprogrammer and on the computer. The situation to he simulated must he well enough understood that model equations are available and provide a reasonahle approximation of reality. The situation chosen for simulation should be one where red-life experiments are too dangerous, too slow, too fast, too complex, or too expensive for the student to do. In some cases, such as display of electron densities from quantum calculations, there may not even be a real experiment that could produce the simulated output. The programmer must make studentlcomputer interactions flexible and convenient-the computer should not get in the way, but rather must be an essentially transparent medium that lets the student focus on chemistry and chemical models. Finally, the comnoter must calculate ranidlv . .enoueh " so that almost instantaneous results can he gotten from realistically complex models. Currently this last is often a stumbling block, hut faster, more powerful microprocessors are just down the road, and numeric coprocessors, such as the 8087 now available for IBM Personal Computers, can achieve considerable speed-up in cases where overall resoonse of a simulation is limited hv calculation speed. Several examoles will serve to illustrate the diverse wavs ill which sin~ulationsare already applied. Gordon Harrow (16) hnsdescrihed the oussihilitv that phvsiral rhemisrrvrould he made a "playgrou~d"withan appropriate collect
