Formative assessment probes can be used to foster productive science discussions in which students make their thinking visible to themselves, their peers, and the teacher. During these discussions, there is an exchange between the teacher and students that encourages exploratory thinking, supports careful listening to others' ideas, asks for elaboration and evidence-based explanations, and acknowledges and respects everyone's ideas. Discussion prompts are among one of our most important formative assessment tools. These tools include six "talk moves." Collectively these talk moves make up a strategy that helps teachers facilitate productive discussions that uncover and probe students' thinking. The six talk moves and their use with formative assessment probes are summarized in this article: (1) Revoicing; (2) Restating Other Students' Ideas; (3) Applying Own Reasoning to Others' Reasoning; (4) Prompting Students for Further Participation; (5) Asking Students to Explicate Their Reasoning; and (6) Using Wait Time.