While small group discussion during undergraduate classes is an important pedagogic strategy, there are two primary concerns for instructors how to monitor the conversation that goes on within groups, and how to ensure that ideas that emerge within the groups become part of the classroom discourse. In this paper, we describe a design-experiment conducted in two sections of the same undergraduate education class, exploring the use of Twitter, and a shared display of the Twitter-chat, to address these issues. We describe three iterations of the use of Twitter in the classes, and our reflections on how it influenced the teaching experience. Data from student surveys indicates that students had minimal experience using Twitter for academic acti...