The work of teacher candidates matters in particular ways to the quality of children's experiences and environments when they teach in preschools. We conducted a mixed-method study with survey, interviews, focus groups, and photographic documentation of classroom spaces, and theorized findings through Bahktin's dialogism and the notion of figured worlds. Ranked survey items confirmed that the physical environments of preschools were shaped by projects stemming from university courses. Although the physical traces of candidates' work were short-lived, ending with student teaching, the classroom climate changes garnered positive social and emotional supports to children in situ that made lasting changes in children's places in the social community of preschool. Dialogues allowed mentors and candidates to reinterpret their images of children and in some cases renew instructional approaches and act against standardized forms of accountability, which limited curriculum and pedagogic choice.