“Where's the Evidence?”

The students are sitting in their seats working individually when I arrive at 7:45 the next morning. As I set up the video camera and microphones there is a buzz of expectation in room, and the students sitting at tables begin whispering excitedly to each other. Laura asks the “passer-outers” to return the papers students wrote the day before. Laura stands at the chalkboard, facing the class, and provides them with an overview of the day’s activity: they are going to use their writing on these papers to create, with their partner, a “report” (a poster) representing their current thinking about the operation of the Cartesian diver system. The students will then share these reports, and their findings, with each other. Laura’s description lasts 26 minutes, and although Jay raises his hand several times, he is not called on and remains silent while Laura talks. Five other students do raise their hands and are acknowledged. Laura’s description of how to write the reports lasts nearly 30 minutes.