Building on Christina Siry and Johaira Lara's account of one teacher's (Johaira's) identity formation, we describe how our own experiences with elementary teacher candidates inform, and are informed by, this account. Chris and Johaira provide a lens that helps us consider how experiences in elementary science teacher preparation courses and in elementary classrooms impact the development of a teacher candidate's identity as a teacher. The course taught by Chris was one in which teacher candidates encountered uncertainty and ambiguity in the teaching process. While uncertainty and ambiguity can be uncomfortable, we suggest that uncertainty and ambiguity can help teacher candidates view science teaching as a process of continuous inquiry. Concomitantly, working within a context marked by ambiguity and uncertainty can prompt teacher candidates to confront--and possibly transform--their own assumptions about students and science. We suggest that the account by Chris and Johaira illustrates the importance of providing teacher candidates with a set of experiences and theoretical tools to assist them in conceptualizing the possibilities of practice as they construct their identities as teachers.