The elementary school teachers personal understanding of science has not been a primary focus of consideration in reform discussions. The purpose of this study is to explore core understandings about science that are held by four elementary teachers, and to examine the origins of those ideas. The theoretical framework for this research recognizes three guiding assumptions: science exists as a set of ideas that have developed over time through competing discourses; teachers play an important role in the science curriculum; and the guiding influences of a teachers understanding of science are...