Bruce Sherwood
Principal Research Scientist, Center for Innovation in Learning
and
Professor, Department of Physics
Carnegie Mellon University
Pittsburgh, Pennsylvania
Bruce.Sherwood@cmu.edu
Students encounter many difficulties in electricity and
magnetism. Ruth Chabay and I have attacked these problems by
developing a new college calculus-based course and a new textbook
(``Electric & Magnetic Interactions,'' Wiley 1995) in which we emphasize
qualitative reasoning as strongly as quantitative reasoning, thereby
providing a conceptual framework within which the quantitative
manipulations make more sense. The course places heavy emphasis on
atomic-level description and analysis, with detailed attention to the
atomic structure of matter and its electric and magnetic interactions,
with special emphasis on polarization phenomena in metals, insulators,
and ionic solutions. Each student has an inexpensive experiment kit
which lets the students perform crucial experiments during lecture,
recitation, or at home, and which permits tight integration of theory
and (just-in-time) experiments. Electrostatics and circuits are
usually portrayed as completely separate sciences, but we unify them
by analyzing circuits directly in terms of the fundamental Coulomb
interaction. Special software helps students visualize electric and
magnetic fields.
A retention test covering the most important basic aspects of introductory E&M was administered to students who had taken the reform course or a traditional course from one to five semesters earlier. Students who followed the reform curriculum did significantly better on this test both soon after taking the course and later. Students in the reform curriculum also did better in traditional problem-solving on a final exam.
Chabay and I are now developing an alternative to the first-semester college course on mechanics and thermodynamics, with emphasis on physical modeling. Textbook homework problems typically begin at a point where all the important idealizations and approximations have already been made for the student. Yet this modeling is the important physics, while the work assigned to the student is mostly formula manipulation. This contributes to the typical student view that physics consists of a large set of magic formulas.
The new course and textbook, ``Matter & Interactions,'' place strong emphasis on having the students themselves engage in the process of modeling physical systems, including computer modeling. Atoms and elementary particles play a significant role in the course. The emphasis on atomic-level description and analysis makes it possible to unify mechanics and thermal physics. Qualitative reasoning plays a major role. As in our E&M course, students do just-in-time desktop experiments, which are closely related to their theoretical models. Opportunities are provided for reflection on larger issues, for example determinism vs. uncertainty. This course responds to the problem that many students with a good high school physics background are bored by the standard college mechanics course.
This work was supported in part by National Science Foundation grants MDR-893367, USE-9156105, and DUE-95-54843.