In the Classroom edited by
Curricular Change Digests
Baird W. Lloyd Miami University Middletown Middletown, OH 45042
Teaching College General Chemistry: Techniques Designed To Communicate a Conceptual Framework
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Ronald J. Duchovic Department of Chemistry, Indiana University–Purdue University Fort Wayne, 2101 Coliseum Blvd. East, Fort Wayne, IN 46805-1499
Typical undergraduate students often see general chemistry at the college level as an insurmountable hurdle. Often they simply dislike the subject or exhibit a dramatic fear of it. With the exception of potential chemistry majors, the vast majority of general chemistry students enter the class simply to satisfy a graduation requirement of their degree program. Little value is attached to the acquisition of new and enhanced problem-solving skills, to understanding the methodology of a physical science, or to exploring the relationships between a physical science and the diversity of nonscientific disciplines that constitute a modern college education. As Beall notes, students commonly approach courses in general chemistry with a number of misconceptions (1): 1. Chemistry is neither interesting nor important to them. 2. Examinations represent the “total” or most significant part of the course. 3. Students tend to memorize equations rather than understand concepts. 4. Chemistry is viewed as simply a mass of facts rather than an activity undertaken by human beings. 5. Students view chemistry as a clearly defined sequence of material involving no controversial topics rather than as a way of thinking about the natural world.
In the face of this set of diverse preconceptions, instructors are confronted with the simple demand to “teach chemistry”. They must both communicate an understanding of the subject matter and overcome a number of major barriers to the learning process itself. Again, as Beall notes (1), this is too often done very ineffectively. The typical lecture delivered to a passive audience communicates too little and dismally fails to inspire the students. Very typically, lectures answer a series of questions that were not asked by the students themselves (2). Further, the lecture’s emphasis on algorithmic problem-solving rather than on conceptual understanding introduces additional obstacles to learning for many students (3). In courses with large enrollments, the Socratic approach is either unwieldy or simply not attempted. Finally, laboratory sessions, which should provide excitement from direct experience, are no more than simple demonstrations that rapidly degenerate into tedious exercises. A variety of attempts have been made to address some of the limitations of the traditional college general chemistry course. Two techniques that have proven particularly successful W
An expanded version of this article is available in JCE Online at http://jchemed.chem.wisc.edu/Journal/Issues/1998/Jul/ abs856.html.
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are exam repechage (from the French; literally, “second chance”) and the grouped laboratory essay. Both methodologies place a premium on conceptual learning, and hence complement the algorithmic problem-solving approach so commonly used not only in general chemistry but also in most introductory physical science and mathematics courses. Additionally, these pedagogical techniques provide increased opportunities for student–faculty interaction, thereby enhancing the apprenticeship relationship between student and teacher so often lost in contemporary education. Exam Repechage An examination should be both a tool that assesses the student’s proficiency in a field and an opportunity for the student to learn the subject matter as completely as possible. It ought to probe beyond simple rote memorization of terms or formulas and attempt to evaluate the student’s integration and comprehension at the conceptual level. In the approach used here, an in-class exam consists of two equally weighted sections. One section contains definitions and questions requiring short answers, matching, and filling in the blanks. In effect, the student is asked to demonstrate a basic level of knowledge. The second section consists solely of problems, which the student is directed to solve in detail, writing clearly each step of the solution and demonstrating explicitly the logic of the solution. Each answer should be conceptually clear and represent a well-ordered approach to the question. The grading of this portion of the examination permits partial credit, placing minimal emphasis on computations (perhaps 10% of the total point value of each problem) and focusing instead on the thought processes used in each solution. Within one week after an in-class examination is returned to the student, he or she may choose to re-solve any problem done improperly in the problem section of the exam and to discuss the corrected solution with the course instructor. Each student choosing to exercise this option of a second chance (i.e., a repechage), is required to write the corrected solution to the problem(s) and to make an appointment (within the one-week time period) to discuss the corrected solution(s) with the instructor. Assistance with the corrections can be obtained from the course text and the student’s notes, from other members of the class, or from the course instructor prior to the time of the scheduled appointment. For each corrected problem, the student is credited with 50% of the points deducted during the initial grading of the problem. Since the repechage applies only to the second half of the examination, a premium is placed on the development
Journal of Chemical Education • Vol. 75 No. 7 July 1998 • JChemEd.chem.wisc.edu
In the Classroom
of problem-solving skills and the clear ordering and presentation of logical solutions. Further, this procedure encourages students to learn from their mistakes and emphasizes that an examination ought to be a learning tool. Grouped Laboratory Essays Writing as a learning tool has been used in a variety of forms in general chemistry courses. As an experiential activity, writing is an ideal complement to the chemistry laboratory session, engaging the student in an active learning process. Critical-thinking essays assigned as homework on a weekly basis are described by VanOrden (4 ). In addition to criticalthinking exercises, VanOrden has utilized fantasy writing (5) as an innovative teaching tool. Cooper (6 ) describes a notewriting (short essays of 100 to 200 words) program in which students write an informal description or summary of an assigned topic. The short length of these essays easily permits their use in a large-enrollment class. In contrast to programs that require writing outside the classroom, Beall (7 ) describes the incorporation of eleven short (5-minute) writing periods in the course of a 40-lecture semester, with topics ranging from simple factual questions to more provocative “thought” questions. Finally, Sunderwirth (8) proposes an extensive writing program both during formal class and examination periods and outside the class sessions. In a general-education chemistry course, five short essays and one longer term paper are required. In the same course and in an introductory chemistry course, all quizzes and examinations require written answers (no multiple choice questions). In the laboratory, students are required to prepare an extensive narrative description of each experiment that includes (i) a statement of the purpose; (ii) theoretical concept or basis of the experiment; (iii) brief description of the procedure; (iv) results; (v) conclusions drawn from the results; and (vi) analysis of errors. In contrast to the above approaches concentrating on the development of communications skills (see also refs 9–12), the grouped laboratory essay approach, in which the writing is completed outside the formal class and laboratory periods, possesses a dual purpose: (i) integration of scientific concepts common to more than one laboratory exercise into a single coherent picture and (ii) expression of these concepts in clear and succinct language. During the course of a 15week semester, students are required to write a total of four essays between two and five typewritten pages in length. Each essay must identify and discuss the common chemical principles or properties demonstrated by the entire group of laboratory sessions (usually three to five experiments). If the group of laboratory exercises demonstrated several basic principles, then similarities are highlighted and contrasts are made. Finally, the essay should identify points of contact between material discussed in the lecture and observations made in the laboratory. In discussing writing in the chemistry curriculum, Rosenthal (12) summarizes Britton’s division of writing into the categories low, medium, and high, based on the degree of abstraction, analysis, and generalization required. Simple chronologies, definitions, and listings of procedures constitute a low level of intellectual involvement. At the medium level,
comparisons and contrasts, summaries, and classification become the chief modalities of thought. At the high level, scientific and scholarly arguments along with careful analyses emerge as dominant themes. The grouped laboratory essays challenge students to perform at the highest levels of writing involvement, with contrasts and comparisons representing the minimum expectation for these essays. Impact, Practical Considerations, and Conclusions The exam repechage made two valuable contributions to the course. First, examinations were clearly seen as learning tools. Second, the repechage offered an opportunity for the course instructor to meet individually with a large fraction of the class. This transformed some fairly large classes into an approximate apprenticeship, making the educative process a personal one for student and instructor alike. The grouped laboratory essays had several notable effects. First, as the semester progressed, there was a steady improvement in students’ ability to communicate in written form. While not the sole focus of these exercises, both grammatical usage and clarity of expression improved with each succeeding essay. Second, many (but not all) of the students were able to complete a careful analysis of the group of laboratory sessions. They exhibited the ability to identify major chemical concepts and to draw parallels and contrasts among the various experiments. That is, many were capable of writing at Britton’s medium level. Moreover, a small number (perhaps 10%) of students were able to identify connections between lecture material and the laboratory sessions and consequently these students completed the course with a more integrated view of the conceptual framework of the science. This smaller group of students achieved the highest level of intellectual involvement in the writing process. However, implementation of these pedagogical methods demands both time and determination from the instructor. For even moderate-sized classes, the investment of time required by both techniques is substantial. In exam repechage, the initial grading of the examinations is very time consuming; and the post-exam appointments can easily consume the major portion of one week and may extend into a second week. The grouped laboratory technique can be successful only when the instructor reads the essays carefully and provides detailed comments. Consequently, the implementation of both techniques is severely constrained by class size. Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
Beall, H. J. Chem. Educ. 1993, 70, 10–11. Beall, H.; Trimbur, J. J. Chem. Educ. 1993, 70, 478–479. Nakleh, M. B.; Mitchell, R. C. J. Chem. Educ. 1993, 70, 190–192. VanOrden, N. J. Chem. Educ. 1990, 67, 583–585. VanOrden, N. J. Chem. Educ. 1990, 67, 1052. Cooper, M. M. J. Chem. Educ. 1993, 70, 476–477. Beall, H. J. Chem. Educ. 1991, 68, 148–149. Sunderwirth, S. G. J. Chem. Educ. 1993, 70, 474–475. Wilcox, S. W. Eng. Educ. 1980, 70, 750–752. Olmsted, J. J. Chem. Educ. 1984, 61, 798–800. Bailey, D. N.; Markowicz, L. J. Chem. Educ. 1983, 60, 467–468. Rosenthal, L. C. J. Chem. Educ. 1987, 64, 996–998.
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