This paper highlights the second phase of a multi-university research project focusing on improving secondary prospective mathematics teachers' abilities to respond to student thinking. This work is based on an Interview Module, created by the authors, which showed gains in prospective teachers' (PSTs) abilities to attend to and interpret student thinking but did not show the same gains in their abilities to respond to student thinking. The Interview Module originally included a pre-post-video, readings, discussion, and one-on-one interview with a secondary student (Lesseig et al. in Math Teach Educ 5(1):29-46, 2016). This second phase adds a take-home assignment based on solutions from the secondary students who were interviewed in Phase 1. This take-home assignment was designed to specifically improve PSTs' abilities to respond to student thinking. Results indicate that gains were made in their ability to respond, as was intended, but, unexpectedly, greater gains were also found in their abilities to attend to and interpret student thinking compared with Phase 1.