The purpose of this research was to investigate and describe concrete examples of Year 1 students engaged in "good thinking" and to generate assertions about the ways teachers can foster habits of "good thinking" through science. The research design was a multiple case study of 32 lessons, of which four are analysed in detail in this paper. The results suggest that young children engaged in good thinking are likely to explain and demonstrate their ideas and actions and to make suggestions for solving problems. Children engaged in "good thinking" also are likely to highlight discrepancies, adopt new ideas, and work collaboratively. The results indicate that teachers can foster habits of "good thinking" through science; first, by accepting difficulty as an integral part of the learning process, second, by encouraging children to explain and talk about their ideas and, finally, by creating an environment where thinking is a valued classroom process. (Contains 2 tables and 2 notes.)