We engaged preservice teachers in a redesigned mathematics field experience with a central focus on children's reasoning through teaching experiments and purposeful reflection on practice through Lesson Study. Indicators of effective teaching were examined through analysis of lesson plans and enactment, comparing student teachers who participated in the revised approach with student teachers in conventional forms of field experience. Findings suggest that teaching aspects fostered by the revised approach during the field experience had a positive residual effect during student teaching. Those who took part in teaching experiments and lesson study had lesson plans that provided for sense-making, encouraged collaboration, and included investigative mathematics to a greater degree than those in the conventional group. Those in the revised group implemented lessons during student teaching that were more student-centered and considerate of classroom culture than those who took part in the conventional field experience. We provide recommendations for designing field experiences.