Maintaining shared understanding in classroom interaction is challenging for both teachers and students. In this paper, we consider the role of teachers' gestures in promoting shared understanding. Our specific aim was to document ways in which teachers use their own gestures to support students' contributions to the classroom discourse. We present three illustrative cases that represent the range of variation in teachers' use of speech (i.e., repeating the students' speech vs. not speaking at all) and variation in the spatial positioning of the teacher, the student, and the referents of the student's speech. We argue that teachers use gestures, both to ensure that they share common ground with the individual student who is speaking and to foster common ground among the class as a whole.