The mathematics education literature occasionally suggests inviting students to the classroom board to share results of their inquiry. In this conceptual chapter, we discuss how this practice can be investigated. Linking across different bodies of literature, we illuminate the special status of boards in mathematics and its teaching, and elaborate on the affordances of a board as a physical place
... [Show full abstract] for mathematizing. Building on the commognitive framework, we conceptualize the practice in terms of situations where students engage in a public communicational activity and generate narratives about the mathematical objects of their inquiry. We refer to these situations as "mathematizing at the board" and argue for special opportunities that they provide for students' learning. To present the conceptualization in action, we use two proofs that students generated at the board as part of our ongoing project on topology teaching and learning. We use this data to illustrate the analytical potential of the commognitive construct of routines to capture nuanced differences in students' mathematizing at the board.