This study reports on an effort to improve the teaching and learning of physical science for prospective elementary teachers. As part of the effort, a new constructivist science curriculum model was introduced for field testing at a large midwestern university. The purpose of the study was to build a research base to guide future science teaching and learning practices through the exploration of how and why students respond to the new curriculum and how the instructors reflect on the effectiveness and the obstacles of the new approach. The findings of this study suggest that it is important for preservice teachers to have some successful experience in conceptual change concept teaching. The necessity of appropriate alternative assessment techniques is also indicated. Contains 12 references. (DDR)