Computer Simulation In Science Teaching: Pros And Cons

Undergraduate science labs were once pretty predictable—pulleys and circuits, rocks and minerals, titrations and unknowns, bacterial brews and pickled piglets. But today’s science lab student, in one short session, can breed a litter of kittens, trace the trajectory of a fall on Venus, predict the timing and force of an earthquake or a volcano, “experience” a car crash or being born, or, in the rather unscientific prose of one catalog, “empathize with the hopeless struggle of an ant caught in the glue of a sundew.” All courtesy of interactive video simulations, of course. Such tools, widely recognized by scientists working in industry and academia as a means of investigating phenomena that are too expensive, time-consuming, or otherwise unreasonable to examine in actuality, are now increasingly being used by teachers of undergraduate science courses as well. Computer simulations undoubtedly have expanded the repertoire of the science lab, but do they preserve the creativity and questioning, the wonder and fun, that are the essence of scientific discovery? The answer depends both on subject areas and on how extensively simulations are used. “For some topics they’re wonderful, especially things that are random, such as diffusion. You, type in the temperature, how big you want a pore in a semi-permeable membrane, and the speed the molecule moves. The diagram shows molecules going across the membrane at different speeds. But for strictly biological processes, ‘such as cell division, simulations become, although still valuable, more simplistic and limited,” says Randy Moore, chairman of the biological sciences department at Wright State University in Dayton, Ohio. Simulations as Supplements Simulations are most valuable, many believe, when teamed with actual experiments. A program to build different amino acids by replacing R groups or to construct different protein primary sequences can supplement an electrophoresis experiment, for example. The “heart simulator,” which traces cardiac blood flow, is the physiological complement to a standard dissection lab. Health-oriented simulations allow students to integrate interventions without harming volunteer victims. A cardiopulmonary resuscitation simulation presents cardiac arrest scenarios, with the user selecting actions at various decision points. The screen shows what happens in the event of a wrong choice. In genetics, simulations can compress time. Ernest Jackson, an engineer with a Ph.D. in genetics, developed software called “Mendel’s Computer Lab” when he taught a genetics lab course. The program was developed as a reaction to his frustration at not being able to keep pace with the lecture schedule, because the fruit flies he was using refused to appropriately tailor their sex lives. A mapping regimen that normally takes five weeks can be done on his software in two hours. The computer lab shows fly phenotypes so clearly, Jackson claims, that human error in misclassifying flies is eliminated. Jackson’s is one of sev eral available genetics progtams, with such colorful names as Heredity Dog, Flygen, and Mendelbugs. But Jackson convincingly maintains that his lab gives students a very different perspective from that obtained by doing conventional experiments. “In a typical lab, students are told the basic rules of inheritance, and expected to memorize and use them. They are given genotypes of flies, and must predict results. They get very little experience in discovering basic principles.” But by setting up crosses on the computer and splitting the screen to display genotypes, students see how recessive traits are indeed “hidden”—and derive the rules by visu- alization and reasoning, not memorizing. The computer also transcends earthly constraints. “The student can pretend to go to Mars and encounter new kinds of fruit flies. They must determine the genetics. Unbeknownst to them, the males are tripbid and the females diploid, and the crosses yield crazy ratios,” Jackson says. But if one takes away the preparation and messiness of experiments, and even human error, is it really science? “I think students should look at actual flies, simple things like distinguishing different mutations. They should make their own medium, watch the larvae grow. Students get concerned over the flies, and are genuinely unhappy when they die,” says Alice Jacklet who prepares flies and all their accoutrements for 270 budding biologists each semester at the State University of New York, Albany. Simulation Stand-Ins But all the preparation involved in biology experiments can over- whelm even a stalwart hands-on supporter like Jacklet. “I have to have 30 million flies in 12 days. I stand over them, chanting, ‘Grow, grow!’ “ At ‘times like this, she says, being able to punch a few keys and watch the generations whiz by sounds enticmg. Dick Rayle, who conducts a genetics lab at Miami University in Oxford, Ohio, switched to simulations seven years ago, when he began writing his own programs. For example, he simulates Beadle and Tatum’s classic deciphering of biochemical pathways using nutritional mutants of fungus. “You don’t have to wait for the things to grow up. You get mutations, see which nutritionally supplemented media they grow on, group the mutants, and eventually see where they end up in the biochemical pathway,” he says. But simulations can be so enticing that it’s tempting to use their instead of experiments. And sometimes this can stifle the very creativity that simulation supporters cite in their major advantage. For example. a product in a video series called “Experiment:BIOLOGY” provides views through a transmission electron microscope of protozoa. The advertising claims this experience to be superior to the old standby of locating protozoa in a drop of pond water collected by the student. The difference is that the video program, no matter how sophisticated, is purchased and provided—not discovered. Similarly, a video observatory replaces a telescope, a molecular ammator stands in for old-fashioned Tinkertoy molecular models, and bacterial serial dilutions are done on a screen. But seeing rock formations and fossils via a “video field trip” cannot possibly compare to three-dimensional reality. For example, New York City high school science teachers often send students to look at fossil-bearing rocks in downtown buildings—illustrating vividly that discovery can be made even in the most unnatural places, an experience that cannot be duplicated electronically. When Simulations Shine Simulations can, however, stand alone in cases in which they offer exploration not otherwise possible. Physics simulations, for example, enable one to drop water bombs on a forest fire; describe a vertical flight path near the earth; follow projectiles; fly a plane; follow radioactive decay; and alter such variables as wind speed, gust frequency, and the .tension and length of support structures of a collapsing bridge. For earth science, a simulation offers unusual views of eclipses, moon phases, and tides—not as exciting as the real thing, perhaps, but able to be summoned up according to instructors’, and not celestial, time-tables. “In chemistry you can do experiments you really couldn’t do in the lab—those that require elaborate equipment, such as extreme pressures, or those involving fires, toxic chemicals, or explosive reactions. In one program, you can pick the conditions to give a dust explosion, and see a video of this happening under the conditions selected,” says David Stehly, who directs 150 students in general freshman chemistry each semester at Muhlenberg College in Allentown, Pa. Simulations can free the environmental scientist from reliance on natural disasters to study some problems. In an interactive video called “Pollute,” for example, students manipulate water temperature, type of waste dumped, rate of dumping, and type of body of water, and witness the effects on the oxygen content of the water. Lev R. Ginzburg and H. Resit Akcakaya of Applied Biomathematics in Setauket, N.Y, and the department of ecology and evolution at nearby SUNY-Stony Brook, explore a new ecological problem through simulation—the invasion of an ecological community by genetically engineered microbes. Although sim- ulations in the past have addressethe infiltration of new species, introduction of a genetically altered organism is breaking new ground—the first such deliberate releases occurred in 1987. After introducing the new organisms, the program keeps track of the number of species and the sizes of all populations. Not unexpectedly, the genetically engineered variant replaces its less fit progenitor. With hundreds of deliberate release experiments winding their way through the red tape, this simulation has a viable market among researchers, but it also may be of value in biotechnology classes. The field that stands to be most illuminated by computer simulations is evolution. With the exception of unusually fast genetic change, the expanses of time needed to witness evolutionary events in multicellular organisms are far too vast to be practical. Here again, the ability of simulations to telescope time is valuable. Several programs monitor how genetic change over many generations alters populations and, ultimately, evolution. “You can show natural selection, generation after generation, in a matter of seconds. The student enters the selective pressures, or random matings, for this population versus that. These programs are wonderful,” says Randy Moore. In a program dubbed “Evolve,” for example, students vary the size of the starting population, survival and reproduction rates, and emigration and immigration. Carrying capacities and predatorprey relationships are also effectively simulated. The age-old question of how life originated is also particularly well-suited for simulation, as the many variations on the primordial soup . experiment of Miller and Urey attest. It seems that sooner or later, computer simulations will find their way into many science teaching labs. But, at least for now, cost is a big factor. Jackson’s computerized genetics lab, at about $60 per student, might be acceptable in a genetics class, in which the program would be used in each session, but is too expensive for the few weeks allotted to genetics in general courses such as Jacklet’s. Still, Jackson sees a market in the many universities he surveyed that have canceled traditional lab programs because of the difficulty in equipping them. Perhaps directors of science teaching labs should take a cue from evolution, which teaches us that there is safety in diversity. A wise combination of computer and downand-dirty, hands-on experiments may be best. Flies can die or remain stubbomly celibate, and computers can crash. But if an instructor is equipped with both, chances are that the session not only will be saved, but also will excel in both excitement and imaginativeness—both vital for nurturing the next generation of scientists. Ricki Lewis s teaches biology at the State University of New York, Albany.

Computer Simulation In Science Teaching: Pros And Cons

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November 1989

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