A teacher's ability to attend and respond to student thinking is a key instructional capacity for promoting complex and deeper learning in science classrooms. This qualitative multiple case study examines 14 preservice science teachers' (PSTs) responses to learning opportunities created to develop this capacity, as provided by a teacher preparation program. The PSTs engaged in multiple cycles of designing assessments and analyzing student work in coordination with clinical experiences in the field. Drawing upon the notions of responsiveness and noticing, we analyze teaching episodes for whether and how the PSTs in this study attended and responded to student thinking in instructional contexts. Several teaching episodes provide evidence of PSTs' productive responsiveness--suggesting modification in specific elements of instructional design to create better conditions for advancing students' scientific thinking. In general, however, the episodes suggest uneven success in PSTs' responses to student thinking. The findings point to two considerations in designing learning opportunities to enhance PSTs' responsiveness: (a) the use of high-quality assessment tasks that make student thinking visible and (b) helping PSTs to reframe the problems by deprivatizing PSTs' interpretations of student responses.