The purposes of this dissertation study are to better understand what specific types of scientific knowledge and practice three elementary teachers exhibit, and to examine how they use their scientific knowledge in their classroom teaching practice to provide students' opportunities to learn science when teaching condensation in the context of a unit on the water cycle. By comparing and contrasting three cases of elementary classroom teaching, this study discusses what kinds of scientific knowledge and practice are fundamental for teaching elementary science for scientific understanding.

The data include structured interviews (content, pre- and post- observation, and stimulated recall), videotaped classroom observations, and collections of teachers' and students' written artifacts. Data were collected prior to, during, and after the three teachers taught condensation to fifth grade students. The data were analyzed in three contexts: interviews, teaching practices, and students' classroom activities. This made it possible to clarify which characteristics of teacher's scientific knowledge influenced which aspects of their teaching practice.

Data analysis shows that teachers' scientific knowledge were closely associated with their teaching practice and students' classroom activities. Two characteristics of the teachers' scientific reasoning emerged as especially important. The first concerned how teachers connected observations of condensation with patterns in those observations (e.g., condensation occurs when warm moist air cools) and with explanations for those patterns (e.g., condensation is water vapor that changes to liquid water). Two teachers were careful to connect observations with patterns in their own thinking and in their classroom teaching. One of those teachers also connected the observations and patterns to scientific explanations. In contrast, the third teacher focused on listing scientific terms with little elaboration with specific observations and patterns.

The second important characteristic of teachers' scientific reasoning concerned their views of science. One teacher enacted a largely inductive, empirical view, helping her students to observe examples of condensation, to find patterns in their observations, and to label the patterns as condensation. The second teacher engaged the students in a detailed series of experiments and data-based arguments designed to demonstrate that the liquid water in condensation was originally water vapor in the air. The third teacher focused on teaching students facts and vocabulary from authoritative sources, including their textbook and dictionaries.

This study discusses what it means to have a deep understanding of fundamental science for elementary teachers. Making connections among observations, patterns, and explanations is important for students to understand the scientific world. Scientific practices, inquiry and application, play an important role to help teachers and students connect observations, patterns, and explanations. The implications to elementary science teacher education are discussed, considering how we can prepare elementary teachers to use scientific knowledge in their teaching practice.