edited by: DAVIDA. PHILLIPS Wabash College Crawfordsville, IN 47933
PRUDENCEPHILLIPS Crawfordsville High School Crawfordsville, IN 47933
Why Teach Chemistry with Computers?
Why I Teach Computer Science to Chemistry Students
Paul A. Cauchon Canterbury School New Milford, CT 06776
G. Scott Owen
In September 1972 1 assigned my first CAI program, an interactive drill on metric unitti. For 13 years I have continued to exnand the role of comouters in mv chemistrv" course because carefully selected appiications sigkficantly improve my teaching efficiency. I am sure there is a limit to the ways in which computers can enhance a chemistry course, but I do not think I am near i t yet. In this paper I shall outline some of the reasons why I teach chemistry with a computer. Consider the one thing we all could use more of that would make us more effective-in the classroom. Is it higher pay? More money for lab equipment? Smaller classes? While any of these might have a positive effect, depending on our current salaries, facilities, or class loads, I think there is one universal need that annlies .. to all of us., reeardless of our situation-we need more time. More time to correct papers p r o m ~ t l v so , students can see what thev did wrone while they ;an-still remember what the assignment was aliabout. More time to set un (and take down!) demonstrations we need to make chemistry come alive fo; our students. More time to provide the monitored practice manv students need to develop the vocabulary and problem-solving skills essential to success in an exact science. More time to go over individual lab data and results as they are being recorded, obviating some of the errors before the lab report is written instead of just pointing out what should have been done after it is really too late to do much of anything about it. More time to edit tests and other handouts we nrenare so they are free of errors and contain no ambiguous questions or directions. I use comouters to helv with all of these tasks. therehy gaining a good bit of that precious commodity nond of us will ever have enough of. I see computers as catalysts for the learning process, since they speed up the "reactions" I am looking for in my classroom. In a sense they lower activation energy and open new pathways, offering students a more favorable learning environment for many of the concepts, skills, and techniques I consider important. As a result, they enable me to make better use of mv student contact time and to function more as a consultant and director of learning resources than as a drillmaster or source of information. Of course, just as catalysts are very selective for the processes they enhance and involve reaction mechanisms that are not alwavs well understood, so the software must be carefully matihed to a particular learning activity, for we still have a long way to go in being able to predict how effective a particular program will be before we have seen how students react to it. Probably the single most important advantage offered by computer-based instruction is immediate feedback-the ability to process input instantaneously and inform the stu~~~
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Journal of Chemical Education
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Georgia State University University Plaza Atlanta, GA 30303
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Why do I teach comnuter science to chemistrv students. how do I choose the pakicular topics I cover, and what do I expect the students to learn from this subiect? First. let me tell you what I do teach. I teach aspects of computer science in two different courses. In our instrumental analysis course (which is team taught) I teach a section on optical spectroscopy and cover computer-instrument interfacing, including an experiment in which the students acquire and display a spectrum on an Apple microcomputer interfaced to a spect~o~hotometer. This is important because the students will probably be using such systems when thev do research. either in industrv or academia. The main computer science dose is in a soecial one-unit course. In this c o k e I do a brief introduction to computer hardware (central processing unit, main memorv, mass storage, and inputloutput devices) and software (operating systems, system utilities, text editors, and language compilers and interpreters). 1 [hen teach programmini in P R S C R ~ on a VAN 11 780 superminiwmputer ( I do not have enough micro's available to use them in the course). I believe that it is extremely important for chemistry students to feel comfortable with. rather than mvstified bv. computers, and to understand both their useiulness a 2 limitations. Students should realize that most "computer errors" are actually human programming errors. They should also realize the limitations of computers, both in numerical precision and in processing poor information, summarized in the well known expression "GIGO", or, "Garbage in, garbage out". I use the compiled language Pascal, rather than interpreted Basic, for several reasons. First, I feel that it is important for students to use a text editor, since one of the most important functions of a microcomnuter. even for chemists. is as a wordprocessor. (I do not know what I would do with: out my IBM PC and Wordstar.) I t is a little more difficult to use a compiled language because you must go through the process of learning to use a text editor to create the source code file. However, students learn the text editor in a short time, and this does not really seem to be an obstacle. The second reason I chose Pascal is that Basic was a language designed in the 1950's that incorporated the knowledge of that era. Pascal was designed a decade later and is much more up to date. In fact, except for very large program development, Pascal includes almost all of the current thinking in computer language design. (Continued o n p a g e 137,eol. 2)
dent a t the "magic moment" where the simulation is leading, or whether a response is correct or not. That moment is, of course, when thk student is thinking about the question being asked, not three days later when there is little chance of recalling exactly what line of thinking led to a particular result. One area where real-time responses are particularly important is in the lab. Whenever my students do a quantitative experiment.. thev. are expected to run their data and resultsthrough a program t i a t checks the format of their data-units, significant digits, reasonahleness-and the accuracy of their calculations. Specific errors are pointed out so the student can take positive, corrective action before the report is submitted. I believe that a computer program that "refuses" to accept results expressed with the eight "siguificant" digits froma pocket cal&lator has a positi;e andmore lasting impact on a student than my red pencilled comments on a lab report addressing the same problem. This is true for a very simple reason-the computer identifies the error and makes you correct it but does not "take off' for it! How many of us require our students to correct their errors on a paper and turn the paper hack in for another evaluation? This inlab checking procedure also helps students distinguish among errors in concept, ~rocedure.and format. And finallv. i t evacuates the overail r&t to see.if the experiment shouid be done over while there is still time to do so. Intearatine the computer into the lab in this manner gives me more time to focus my attention on the organization, clarity, and depth of understanding demonstrated by the report-aspects of student performance I do not want relegated to machine evaluation. When the computer is used as a demonstration tool, not only is preparation time reduced by several orders of magnitude, but additional benefits become apparent. Properly designed simulations present the opportunity to vary parameters in order to pursue "what-will-happen-iP' questions, without consuming valuable class time to calculate the results. For example, early in my discussion of chemical equilibrium I use a simulation of the Haber synthesis of ammonia' and let the class select operating pressures and temperatures. I rely on my micro t o carry out the complex computations of reaction speed and percent yield in asecond or two, so that the behavior patterns can be discovered instead of . iust . promulaated. Or. a discussion of the relationship hetween concen&ations, 'dissociation constants, and acid-base titration curves is more meaningful when students can suggest the values to be tried and see the plots done "live," via a dynamic curve-plotting program,Z instead of being restricted to a few carefully but tediously prepared transparencies that show only a limited range of possihilities. Computer-based demonstrations cannot and should not replace live reactions across the board-no computer simulation can approach the awesome spectacle of a thermite reaction, for example. But the advantages they offer make them highly effective attention-getters and discussion vehicles, and that is what I want more of in my courses. Of course, word vrocessina offers time-savine benefits to teachers of all discfplines. ~ r t h o u of ~ hmore adkiuistrative use than instructional, i t is one of the greatest time-savers of all. Gradually my file of dog-eared ditto masters containing all the tests, quizzes, and clever handouts from years gone by is being phased out in favor of floppy disks. The test that worked last year will almost work this year-all it needs is a few changes-not too easily done on a stencil, but almost trivial with a word processor. I know that the quality of the handouts my students receive has gone up dramatically
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Cauchon, P. A. "NHTHREE-A Computer Simulation of the Haber Synthesis," Sci. Quest. April 1982. 2Breneman. G. L. J. Chern. ~ d u c1974,51, . 812.
Aside from the pure computer science aspects, I feel that programming teaches certain problem-solving skills. The students soon realize that I am correct when I tell them that the computer is fast but extremely stupid, as expressed in the programmer's lament, "Curse this computer! I t never does what I want it to do hut only what I tell i t to do." The students soon learn that, in order to write a correct computer program, they must completely understand the problem and develop an appropriate algorithm to solve it. There is no room for partial understanding or ambiguity in computer programming. This seems to help in the general development of logical and problem-solving skills. In the course, I incorporate some numerical analysis techniques (linear least squares, matrix manipulation, numerical integration) as programming problems. This helps t o refresh (or teach) some valuable skills while the students are learning programming. Since these calculations would be very tedious if done manually, this demonstrates the advantage of using a computer for arithmetic type problems. The students also learn to perform large tasks, e.g., the writing of large computer programs by breaking them down into smaller subtasks (computer subprograms such as Procedures and Functions). The Pascal language is particularly suited for this as i t was designed for modular program development. In summary, I teach computer science to my students to make them comfortable with, and to help them realize the advantages, disadvantages, and limitations of, one of the primary tools of modern society. I also feel that the type of thought processes required in computer programming will help them in other problem-solving areas.
Scnt Owen received his BS in chemistryfromHervey MUW College and his h D in physical chemistry from the University ol Washington. Aner ~OrtdDctoralwok in biaohvsical chemisbv at the GBoroia InstiM e oi Tecnnoiogy, ne moved to At.anla Univeroty. where hm pr mary researcn area 9raa.a ly evolved to computer spplcat ons in cnemcal eorcatlonan0 reseam in 1984 he moveotoGeorg a Srate n, versoty. where he has a joint appointment in computer science and chemistry.
Pad Caufhon teaches chemistrv and cornouter . science at Cantsr0.v Schoo m he* M410ro. CT rle s me aAhor ol ' Cnemlstry Woth a Computer 'an0 severa ancies on the Jre of compLters in edwatmn. Currenl y the char 01 lne DwCHED Commnee on Comp~ters'n Chemical Education. Cauchan was insnumental in establishing the very popular oneday CCCEISERAPHIM workshop series for high school chemistry teachers. He received his BS from Providence College and his MAT from Brown University. ~~~
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since I discovered the world of word-orocessine, How often do we use a test containing typographical errors, misleading statements or questions that really are not all that pond. simply lwcnusr we do not haveenvuih time to retype i t Y ~ h e same computer that delivers a tutorlal on alkane nomenclature and simulates the Haber process also runs the word processor that makes editing not only simple but also fun. There are, of course, many more applications of computers to chemical education than I have identified here. But, whatever the application, I am convinced that the computer, more than any other instructional aid, enables me to work more effectively with my students, and this is what I am most concerned about as I plan my teaching strategies. Volume 63 Number 2
February 1986
137
