Physics education research consistently demonstrates the need for students to actively construct new models of physical phenomena if learning with understanding is to take place. Some of the activities that are most conducive to this type of learning include engaging the student in dialogues which expose their previously held views and allows the students to construct new models to replace their old views. However, a large lecture format is often not conducive to an active learning approach. While change from the traditional lecture/lab style of teaching may be desirable, there are typically many structural barriers to creating an active learning environment in physics courses. Many large research universities teach upwards of 1000 students a year in these introductory courses, making reform difficult. In this project, our goal is to address both of these problems by developing and fully implementing a new large introductory physics course that facilitates, rather than hinders, students' construction of physics knowledge, yet works within the constraints of a research university.

Currently, we are preparing for full-scale implementation of this new course in the fall of 1996 at the University of California, Davis, having completed the second of two full-year trials of 100+ students in the spring of 1996. We provide a brief overview of the project in what follows.

During the period from 1990 through 1994, we experimented with limited changes to the laboratories of the 1200+ student per year college physics course for biological science majors at UC Davis. While many of these changes produced improvements in the students' grasp of physical concepts, we concluded that even greater improvements were possible by redesigning the whole course. We considered modifications to each of the major aspects of the traditional course. These aspects included the gross structure of the course (how much time is spent and what students actually do in lecture, discussion, and laboratory) as well as how students are assessed, what physics content is included, how that content is sequenced, and the type of learning resources students use.

Probably the most significant change we implemented in the course was to move from three 50 minute lectures a week combined with one two-and-a-half hour laboratory in the traditional course, to one 80 minute lecture a week, and two two-and-a-half hour discussion/laboratories (DL) a week. With this change, the bulk of the instruction was moved from the lecture to the teaching-assistant facilitated DL section. In a typical DL section, the students are engaged in various inquiry-based activities that help them develop useful models of physical phenomena. Each of the activities usually includes an out-of-class preparation portion, in-class small-group discussion and experimentation, and both in-class and out-of-class problem solving units. Within the reduced lecture, it is no longer possible to "cover all the material" the traditional way. Instead, lecture is used for weekly student assessments in the form of 20 to 25 minute quizzes, framing and extending the work that the students previously carried out in the DL, and setting the stage for future work in DL.

Along with the changes in the structure of the course, we also made changes in the content sequence, the use of course materials and the methods of evaluation. In the first quarter the content focus is on systems and interactions and energy conservation, with second and third quarters focusing more specifically on the details of the interactions. We eliminated the traditional text book in favor of customized learning resources, both paper and web based. The method of student assessment was changed from traditional midterms consisting primarily of algorithmic problems based on lecture and textbook examples, to weekly twenty-five minute quizzes, graded on a rubric scale. The quiz items have a combined focus on conceptual understanding and quantitative problem solving. Students performing below a satisfactory level are encouraged to resubmit their work for additional credit.

We have found that TA training is critical in such a course. Since a large portion of the learning takes place in the TA facilitated DL section, it is imperative that the teaching assistants be provided with proper training and written detailed instructions to help them properly facilitate the DL sections. Twice weekly meetings led by the head TA and the lecturer help the TA's to avoid problems that are specific to a given DL.

From our experience with the two one-year trials we have found that students readily adapt to the features of the new course and that many students change their learning approaches and habits. Lastly, we emphasize that it is possible to make these changes in a large introductory course for science majors and is resource neutral in steady state.

We acknowledge the contributions made by the teaching assistants involved in the developmental stages of this course. We are especially grateful for the continued support of the Department of Physics. Partial support for this project is provided by the University of California, Davis Office of the Provost --Undergraduate Studies and by the National Science Foundation under Grant No. DUE-9354528.