Highlights
edited by SUSAN H. HIXSON National Sdence Foundation Washington, DC 20550 CURTIS T.SEARS, JR. Georgia State Univenity Atlanta,GA 30303
Projects supported by the NSF Division of Undergrclduate Educcltion Dynamic Visualization of Chemical and Instructional Concepts and Processes in Beginning Chemistry Patrick A. Wegner and Andrew F. Montana Department of Chemistry and Biochemistry California State University, Fullerton
Students require conceptualization and visualization skills as well a s mathematical and problem solving skills to learn chemistry. Additionally, learning chemistry requires the ability to integrate different representations of chemical phenomena. Chemical concepts and processes normally are treated from several perspectives--macroscopic, molecular, mathematical (symbolic),and graphical. The understanding and integration of these viewpoints yield chemical insight. Chemistry students may have difficulty integrating these representations because they commonly are treated separately and consecutively. Apremise of our work is that if these representations are presented concurrently with their relationships emphasized, the students' ability to integrate them would be enhanced. We are developing instructional materials that will help students to 1) improve their conceptualization and visualization skills
and 2) integrate the macroscopic, molecular, mathematical and
graphical representations of chemical concepts.
Self-contained units are being prepared that treat selected topics in beginning chemistry. A self-contained unit is called a dynamic instructional visualization unit ( D m ) because animated graphics play a key role both in its preparation and function. Not only are dynamic chemical processes visualized a t the molecular level, but additionally, the other representations that are normally treated separately are presented. Hence, the acronym D I W also connotes the important capability of the materials to present concurrently "diverse uiewpoints" of chemical phenomena. D I W s have a general set of design characteristics. A DTW normally will 1) depict one or more dynamic chemical processes; 2) dynamically intraconnect some or all of the macroscopic,
molecular, mathematical, and graphical representations of the phenomena under study; 3) be interactive, responding appropriately to user choice and input, and being significantlyunder the control of the me,'.
The D I W s are designed to be easily used in a variety of institutions and in various curricular arrangements. Currently, the Macintosh platform is our focus of development; ultimately D I W s will be accessible from DOS systems as well as Indigo workstations.
Three types of D I W s are being developed: a lecture tool designed to assist the instmdor in presenting a concept; a lecture am~lificationthat elaborates the lecture tool. allowing the'st"dent to review and further explore the material: and, a todc luloriol. A lecture tool has a flexible design so that the instructor can control the visualization and the pace of animation, and highlight various sections. The unit contains minimal textual material in order to allow the instructor to provide commentary as i t is displayed. An interactive lecture amplification unit is intended for individual use by a student. It contains more textual material, a much wider range of examples showing special cases not covered in lecture, and guidance and highlights not present in the lecture tool unit. The student is able to control the instructional sequence, repeat the visualizations or any part of them, and change both the speed and pace of animated sequences. Atopic tutorial unit is a combination and elaboration of several sets of lecture t w l and lecture amplification units coupled with extended descriptions and explanations. Some topics for which D I W s have been completed or substantially developed include: the phase diagram of water; formation of hybrid orbitals; titration of a strong or weak acid using a colorimetric or a potentiometric endpoint determination; distribution of gas phase molecular speeds; a dynamic representation of water; and the dissolution of sodium chloride. A series of lecture tool and lecture amplification units on organic reaction mechanisms covering more than 35 reactions has been prepared. Topic tutorials have been prepared for the determination of a Lewis structure and the determination of molecular geometry using VSEPR theory. Acknowledgement This work has been supported under the National Science Foundation award DUE-9156047.
Environmental Chemistry in the Freshman Laboratoly Susan E. Kegley and Angelica M. Stacy Department of Chemistry University of California, Berkeley
Freshman chemistry laboratory is the first opportunity we have to catch and hold the students'interest in chemist r y Unfortunately, because of the large enrollments in freshman chemistry, we often have the students perform experiments that are designed to be "foolproof," easy to supervise, and easy to grade. While this pathway may teach students certain laboratory techniques, it is less likely to be very successful at teaching them how to think or, indeed, why one might want to think about these things in the first place. At the University of California a t Berkeley, Volume 70 Number 2 February 1993
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we are now beginning to implement a new approach to teaching the freshman chemistry laboratory. Our goal is to introduce environmental chemistry into the laboratory in a way that will expose the students to new ways of thinking about science in general and chemistry in particular. We believe that maximum participation in a laboratory course occurs when students &e allo&ed to explore different ap~roachesto solving a Droblem and make their own decisions about the bestpathway to take. Because environmental issues are so relevant to the students' own lives, this subject matter brings the laboratow out of the ivow towers and into their backvards. Environmental chemistry lends itself quite well to"the desired exploratory type of laboratory experience. The problems are by nature not well-defined, a fact which leads students to acknowledge that an answer is sometimes difficult to obtain and depends critically on sampling techniques, time of sampling, method of analysis, and interpretation of data. It enables them to see cbemistry as it %-an everchanging science that relies heavily on the skill and creativitv of the chemist. At present, we offer this special laboratory section to 520% of the freshman chemi&y class in the first semester, however, our ultimate goal is to extend Darts of this omgram tothe entire fresihan chemistry iass. The ladoratom is module-based. where each module focuses on a centrai question that thd students must answer about a site of environmental interest. A "discovew" method of teachine the course is used, in which the students are presented with the question and then must propose answers themselves instead of being presented with a solution. The questions include "Is &is water safe to use as a drinking water supplv?," .. . . "How much lead is in the soil, water. and vegetation near the freeways?," and "Would this site' that was a hazardous waste d u m ~be a safe lace to build a park?" The first laboratory of each module entails a a the site. "Hondine" of the students with their studv trio t sit& is an important aspect of the course. If they have picture in tbeir minds of a reservoir, or a part of the San Francisco Bay, or of a dump site where they are examining the water it rnakek their results more meaningfG to them. They can then associate the"lav of the land" with a particular result, often making the c&nection between
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Journal of Chemical Education
an anomalouslv hieh concentration of a oarticular oollutant and nearby so;rces of the pollutant. ' After eatherine the samoles. the students brine them to the laboratory k r testing. ~ ' v a r i e of t ~analytrcal techniques are utilized, including ion chromatography, atomic absorption spectroscopy, and gas chromatography. Integration of some high-tech instruments into the course is one of the best ways to interest students and to show them the power of modem chemical techniques. Generally, the students work in teams, making tbeir own decisions about where to sample, what to sample, how much a sample should be diluted, and how best to make up standards. The teamwork approach is helpful to all students, but especially useful to low achievers. The stronger students thus serve as role models to show the weaker students what is possible. The instructor and teaching assistants are there to guide the students when necessary, with the specific intent of NOT answering all of tbeir questions right away. Students work individually on data interpretation and written laboratory reports. The final module consists of independent projects, with the t o ~ i cchosen bv the student. The ~roiectsreouire the studeit to use his"or her knowledge if & n p l i n ~site assessment, laboratory techniques, and writing skills to study an environmental problem and present the results of that study to the rest of the class in a Doster session durine the final iaboratory period. We anticipate that the impact of the program on the students in the course will be development of their critical thinking and problem-solvim skills. The combination of learning through discovery and teamwork wdl r l s e their level ofconfidence in what they can accomplish and enable them to take r l broader view of problems and methods of solving them. If they were already interested in science before they took the course, we will have shown them that tbeir interest is not misplaced. If they are students who end up as teachers, businesspeople, or policymakers, we will have shown them enough science and its relationship to technology, development, and preservation of the environment to send them off as informed decision makers.
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Acknowledgment
This work has been supported under the National Science Foundation award DUE-9156123.
