Productive talk is structured talk designed to support students in developing a deep understanding of the content (Michaels et al., 2008): a characteristic of high-quality mathematics instruction (National Council of Teachers of Mathematics, 2014). Students who engage in talk during mathematics class have opportunities to make sense of the mathematics, reason, share their thinking, and hear the mathematical ideas of others (Carpenter et al., 2003). A launch-explore-discuss (LED) lesson structure is one way that teachers can plan for and facilitate productive talk across a mathematics lesson (Stein et al., 2008). This article shares how a mentor teacher, Ms. Harrington, and her mentee, Ms. Gallo, engaged their fifth-grade students in productive talk to develop their students' understanding of volume.