The mathematics education field recognizes the importance of noticing children's mathematical thinking as a means for supporting children in learning mathematics (Sherin et al. Mathematics teacher noticing. Routledge, New York, 2010). Using the existing literature base around teachers' knowledge of children's mathematical thinking and participants' problem posing in response to children's mathematical thinking, we developed the Responding Rubric, which measures four elements of responding to children's mathematical thinking (group or individual responses, consideration of children's existing strategies, anticipation of children's future strategies, and a responsive problem). Using the Responding Rubric, we were able to illustrate elements of teachers' responding skills. Following our presentation of findings, we discuss how our results further our understanding around teachers' noticing skills and provide directions for future research.