In this paper, we extend our previous work on challenges teachers face when engaging with proportional reasoning contexts to investigate two contexts that included four problems for middle grades teachers to solve as well as eight student solutions. Analysis included coding for correct solving of the problem as well as making sense of and determining reasonableness of the associated student work. Results indicate that making sense of student work was not dependent on correctly solving the problem. Determining reasonableness of student work was more challenging for our 32 participants. The think aloud interview, we argue, mimics responding to student thinking in a live setting. Implications for teacher knowledge as well as professional development and teaching will be discussed. [For the complete proceedings, see ED630060.]