As teachers consider what it means for students to "do mathematics" successfully, they must explore their role as teachers in a way that strategically supports students as powerful agents for their own learning. As teachers foster a classroom environment based on agreed-on expectations, they must help students learn how to engage in whole-class discussions that create opportunities for learning among all students. This article shares an initial classroom episode in which classroom expectations were introduced to create an environment for all students in the first author's sixth grade class to engage in meaningful mathematics dialogue. This episode serves as a model for other middle school mathematics teachers as they embark on their own journey toward supporting their students as they move toward purposefully engaging in whole-class discussions.