Comparison of student learning about diffusion and osmosis in constructivist and traditional classrooms

Student learning about diffusion and osmosis was measured at three different universities using a newly developed instrument [Odom and Barrow (1995) Journal of Research in Science Teaching, 32, 45-61] which tests the underlying knowledge of students in addition to their ability to answer factual questions correctly. Instructors at two of the universities taught utilizing the very common large lecture/small laboratory approach. The instructor at the third university taught using a small discussion/laboratory approach which was informed by constructivist theory. Results of pre- and post-testing indicate that students learned about and understood diffusion and osmosis most deeply in the small discussion/laboratory course. Reasons why this may be are discussed and suggestions are presented to help improve student learning in other settings.