Issue 1: The classroom discussion is going pretty well. Students are offering some good comments and more than one hand is in the air. Then a student makes a really excellent observation that opens up a whole avenue of relevant possibilities. You follow-up by calling on a student whose hand has been in the air for some time. Her comment is fine, but it’s totally unrelated to the previous comment. How do you get students to respond to each other’s comments? How do you get student comments to build on a key topic so that it becomes more like a real discussion?