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Hands-onHomework for Large Introductory Physics Courses

Chandralekha Singh

The"Physics Exploration Center" (PEC) at the University of Pittsburgh, modeled after similar centers at the University of California Santa Barbara and Rutgers University, provides concrete experiences with physical phenomena for students in our large, lecture-oriented introductory courses. In the PEC, physics lecture demonstrations illustrating various physical phenomena are transformed into fun, interactive displays. The central objective of the PEC is to provide students with an opportunity to do “hands-on homework problems”. These problems can be assigned even in large classes because students do them at their own convenience and pace. The goal is to help students develop a robust conceptual understanding of the lecture material, challenge their preconceptions by providing contradictory experiences, and introduce them to the scientific method.

The most attractive feature of the PEC is its emphasis on hands-on, self-paced, guided-inquiry based learning. Vivid and memorable experiences in the PEC have both motivational and instructional advantages. The concrete experiences provided by the hands-on activities are very useful for building conceptual understanding of physical phenomena. Even if only one or two PEC homework problems are assigned per week, students will have performed approximately 15-30 by the end of the semester. These hands-on problems improve physical intuition. The interpretation of a problem is easier for novice problem solvers when they have apparatus they can directly view and manipulate as opposed to simply a two dimensional picture in a book. In addition, once a student has played with many demonstrations involving a given physical principle and answered related questions, we find he/she is more likely to be able to use physical reasoning in evaluating other problems involving the same concept. PEC problems also provide a closer look at lecture demonstrations. Due to time constraints, lecture demonstrations are often over before students have had an opportunity to interpret their significance. They can also be difficult to see in a large lecture hall. PEC problems provide students with an opportunity to personally engage in lecture demonstrations they see in class.

We find the Physics Exploration Center to be reasonably cost-effective since equipment can be borrowed from lecture-demonstration inventory. Most of the equipment and infrastructure needed for a PEC capable of serving up to a hundred students already exists in most physics departments. All that typically needs to be found is a space where students can perform the hands-on homework problems. The commitment from physics departments to provide space and cover the extra wear and tear on demonstration equipment is worthwhile since Physics Exploration Center experiences are so beneficial to students. Furthermore, instructors are supportive of the approach since it requires little additional effort on their part and does not require them to change their teaching styles.

The model of Physics Exploration Center that we have developed is suitable for most colleges and universities. The center is open 9am-6pm, Monday through Friday. It is integrated into our "Physics Tutoring Room" for undergraduate students seeking help related to physics courses. During regular PEC hours, the center is staffed by two teaching assistants. The directions for operating the equipment and an explanation of the phenomena involved in each PEC activity is provided with the PEC setup. We have found that providing such written directions and explanations with each setup allows students to carry out the PEC activities with minimal help from the staff. The University has provided permanent space (approximately 600 sq. ft. including the tutoring area) for the PEC. The demonstration equipment used in the PEC is maintained by the Physics Demonstration Resource Center (PDRC) staff.

In order to facilitate integration of PEC hands-on homework into our introductory physics courses, a library of well thought out problems has been compiled and made available to professors. We have also established a website http://www.phyast.pitt.edu/~cls/pec, which contains an expanding database of PEC problems. Currently there are enough for both semesters of the introductory algebra and calculus-based courses. One factor that is taken into account when designing all our PEC problems is that the equipment must be safe for student use without supervision. In addition, we realize that the equipment must withstand handling by several hundred students. Fortunately, much of the lecture demonstration equipment in use is fairly sturdy. After all, it must survive handling by faculty members!