Good classroom discussions rarely just happen. Most good discussions grow out of careful planning and execution.
The nature of the discussion varies depending upon the discipline and the course. Often, a discussion session in a math class is an opportunity to go over homework assignments together. In a philosophy or literature class, a discussion might involve the critical unpacking of a text that all have read before coming to class. The following guidelines are oriented toward the latter sort of discussion.
First of all, decide on the role you will play in the discussion. It's helpful here to consider (again!) your goals for student learning. If one of the goals is that students learn to think critically and creatively about a text or problem in your discipline, then you should consider giving students an opportunity to practice this sort of thinking. If the class is one for students just beginning work in the discipline, you might think it important to model the sort of questions and analysis you expect them to bring to the text. If students are farther along in their studies, you might work more narrowly as a facilitator of the discussion.
Next, you'll need to develop a structure or road map for the discussion. Such a structure is not a verbatim script that you expect your students to follow. In fact, depending on the discipline and course, it's possible that any number of radically different but still fruitful discussions could happen within the structure you develop. Some instructors prepare what is sometimes called a question thread, a series of questions that lead a pathway through a text. Others find this "thread" metaphor too confining, and instead enter a class discussion with several themes, issues, or text passages that they expect the class to address at some time in the discussion, leaving the order to emerge from students' questions and comments.
Finally, you will need to think in advance about how you will prepare students for the discussion. Even instructors who expect students to take the lead in shaping the discussion find that they can help students to take on this role. In fact, in all but the most advanced classes, students are more likely to engage the text productively if they have some guidance from you as the instructor. For example, you might begin a semester by providing two or three focusing questions for each reading assignment. As the class progresses, you might pass this responsibility on to the students, requiring each of them to prepare and circulate discussion questions for one or two classes. Alternatively, you might ask each student to come to class with a question or two about the text that they recognize as important but that they aren't able to answer to their satisfaction. An online discussion forum, be it on a blog or through a course management system like Blackboard, makes it relatively easy for students to make comments and questions available to you and their peers before the face-to-face class begins. Online discussion can help focus the conversations that take place in class.
Once discussion is underway, you will likely find a variety of scenarios emerging over the semester that need your attention. For one, you will find that students' comfort with verbal participation in class varies greatly. Some students will tend to be quiet, while others may dominate the conversation. Dealing with each of these requires attention to the dynamic of the class. To reach the students who are uncomfortable speaking up, you might supplement the classroom with other venues to share their voice, like a course blog. You will also find yourself grappling with moments of silence in response to a question you pose. It is worth trying to accustom yourself to these silences and realize that sometimes students need extra time to stage their responses and work through their uncertainty, especially when dealing with a tricky concept.
Finally, depending on the subject matter you teach, you may find yourself facing an emotionally heated discussion at some point in the class. You should consider working with your students to develop ground rules for discussion for your class, especially if your course content includes contentious topics. Difficult discussions are difficult precisely because most people don't engage them outside of their own small circles of close friends and family—and sometimes not even then. Most students can be afraid to engage in difficult discussions because they might be labeled negatively, express an unpopular opinion, or be pigeonholed as a particular identity or having a particular opinion. In order for difficult discussions to be productive, faculty do need to set ground rules that can guide discussions and encourage students to treat one another with respect. This includes engaging students equally in difficult discussions, requiring students to use respectful language, asking students to avoid personal attacks, and reminding students that people do not need to agree in order to respect one another's perspective. When a difficult discussion begins, you might use this as an opportunity for students to see both sides of the argument by trying out a role reversal exercise in which students are asked to defend the position with which they disagree. Support for difficult discussions also comes from the faculty member's willingness to model open and respectful communication, and to engage difficult questions.