.. ... .-
SUSAN H. H I X S O ~ National Science Foundation Arlington, VA22230 CURTIS T. SEARS, JR. Georgia State University Atlanta, GA 30303
Projects supported by the NSF Division of Undergrcrducrte Educcrtion 4M:CHEM-Multimedia and Mental Models in Chemistry
animations and dynamic graphs of macroscnpic properties in the uooer rieht and lower left auadranu., rcsocctivelv If two or &ee 2 these visualization modes are simult&eously activated, motion sequences in all windows are synchronized. In this example when the tube is placed in the hot water bath, the molecules in the animation begin to increase speed, and the average distribution between monomers and dimers begins to shift toward more monomers. At the same time the partial pressures shown on the graph begin to change. By clicking the "PauseIStart" button the instructor can freeze-kame all windows to allow discussion of actions in any window, links between actions in windows, or predictions of what would be expected later for each representation. When first viewing the animation for heating, most students note the change in average speed and overall composition but many need prompting to observe the dynamic nature of the equilibrium state. Visual overload is avoided by using first single, then pairs, and, only after students know what to expect in each window, all three views together. Using pairs of visualizations is most helpful in establishing links between what each shows and using all three in showing the limitations inherent in each representation. For example, the dynamic nature of equilibrium is shown only in the animation but due to the small numbers of molecules this visualization appears to show fluctuations in equilibrium composition. In addition to such qualitative experiments for each module of 4M:CHEM there are quantitative experiments. For the gas-phase equilibrium example shown here a quantitative pressure change experiment allows determination of the equilibrium constant from pressure and spectroscopic data. The quantitative temperature change ex~erimentuses eas densitv measurements to determine the temperature dzpendence"of the equilibrium constant and subseauentlv the values of the changes in enthal~v.entropy and frke energy for this s y s t e m r ~ ehave foiid the qualitative experiments useful for all levels of courses but A
Joel W. Russell Oakland University Robert B. Kozma SRI International 4M:CHEM is a prototype software environment that utilizes simultaneous, synchronized, multiple representations of chemical phenomena to enhance learning. This approach is based upon learning theories that distinguish experts and novices by the extent and coherence of their mental models for concepts and their abilities to utilize all appropriate aspects of a mental model given a trigger stimulus. 4M:CHEM assists students to build and use the complex models of experts by explicitly showing on a computer screen macroscopic, microscopic, and symbolic representations for chemical phenomena. The prototype system was designed to permit instructors to make classrooms more active learning environments by allowing choices in experiments and experimental parameters as well as their modes of visualization. Features such as the ability to pause and restart experiments at any point and to show single or multiple modes of visualization can be used to promote class discussion and help assure that more students master the instructor's learning objectives for each example. Chemical equilibrium was selected as the subject for the prototype system since this concept is a unifying theme for many topics discussed in introductory and general chemistry courses. Prior studies by ourselves and others have shown that significant percentages of students successfullv com~letesuch courses while maintaining critical misconceptions about equilibrium. Two prevalent ones are that reactions cease at eauilibrium and that wuilibrium systems contain equal amounts of reactants andproducts. We have found that students expressing these misconceptions can utilize LeChatelier's principle to predict shifts in equilibrium compositions and quantitatively solve problems that have very large or very small equilibrium constants. These students have compartmentalized and incomplete models of chemical equilibrium. Acommon screen design, illustrated in the figure, is used for all modules of 4M:CHEM. When a specific experiment for a module is selected, the control window shown at the lower right appears. This window shows the symbolic representation for the system, possible choices for sub-experiments or experimental parameters, and choices for visualization modes. In this case one can elect to heat or cool a sample of N02N20a. Activation of the video button, V, and starting the experiment by clicking the "GoIStop" button will display a video of the actual experiment presented in real, slow, or accelerated time. The motion sequence represented by the still frame in the upper left quadrant of the figure would be displayed as a nearly full-screen size video. Activation of the animation button, A, and graphic button, G, would display motion sequences of microscopic scale
Screen design for the 4M:CHEM program Volume 71 Number 8 August 1994
669
use the quantitative temperature change experiment a s a homework assignment for honors general chemistry. We a r e currently engaged in several investigations extending our work, incuding our research on the differences between exoerts and novices i n their understanding of equilibrium; the ways instructors modify their class6om activities using 4M:CHEM, a n d how students use i t to learn. I n addition, we a r e contextualizing our work by lookine a t t h e twes of reoresentations oracticine chemists use in-their d&iy activities and expldring the ways t h a t new representations and modes of visualization a r e changing the way chemistry is understood and taught. Acknowledgment Partial support fior this work i s provided by t h e Nationasl Science Foundation Division of Undergraduate Education under award DUE-9150617.
Developing a Science Course for Nonscientists on the Chemistry of Art Michael Henchman Brandeis University Waltham, MA022549110 The development ofthis course on Chemistry and Art, as a science course for nonscientists. i s oredicated on a simole idea. Art i s a subject with almost"n&ersal appeal. indeed, our first sensations i n life are of form a n d color. If science can be seen to intensify the appeal of art, then science itself becomes appealing, leading the nonscientist to a n interest in scienceand t i developing t h a t interest. I n this way, art i s used a s a "conductor" to lead the nonscientist into t h e heart of science, to show what science does a n d how i t does it. I n contrast, science, as formal science, i s often forbidding to the nonscientist. Its alien language, so precisely used, makes a difficult subject even more impenetrable. And i t is harder still to reach a level where scientific insight can be recognized. Art can be used to circumvent that. Consider this examole. Beneath t h e paint layers of oil paintings lie the ori@n;l sketches ofthe artists. Since -1980. infrared reflectoeraohv has been able to reveal these buried sketches; and &eie ;ketches can be used to authenticate paintings, to identify artists. Only a little study of optics and spectroscopy a r e needed to understand t h e techniaue of infrared reflectomaohv: a n d t h e powerful applicatibns of this technique immediate incentive to understand the unfamiliar science. Acourse conshucted in this way consists of a series of scientific4snapshots" of what is needed w investigate art.It is a limited mosaic, connected only by the application to art. I t is not the systematic exposition of a topic, as in a general chemi s h course. Its streneth lies i n its form. At all ooints the of science and tce rationale for using seienee'are made clear to the student. As the c o m e omeresses. the effect is cumulative. Once a student learns dhaCscien4 can bring to art, science can no longer be ignored. Many instructors offer courses on Chemistry a n d Art to m e a t effect. As a newcomer. I see m y own aooroach emohasizing the "Art" component to a c t a s a ca
