In this paper, I theorize reciprocal noticing as a relational practice through which teachers and students exchange roles as knowers by reciprocating each other's noticing as they study mathematics concepts. Findings from a unit on measuring time implemented in two classrooms with non-dominant students illustrate how teachers and students--through their reciprocal noticing--mobilize concepts back to previous understandings and forward to possible new meanings. These findings serve to recalibrate the focus on professionalization of the teaching practice by considering how an inclusive understanding of noticing permits to appreciate the process of teachers and students sharing the process of learning mathematics in relationships.