The elementary school teacher's 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 teacher's understanding of science are associated with power. The finding of the study provides evidence that the teachers' science understanding is unique and developed over time. This investigation recommends that teachers' personal understandings become a focus in developing educational opportunities for elementary school teachers. This study further recommends challenging a hegemony related to positivism that exists in science curricula and the use of narrative inquiry as a method of understanding teacher experiences.