I taught Extreme Programming for the first time in about four years. A couple weeks ago, the class was made up mostly of an intact team, about 15 people in all. The interaction was lively.
Last week there were 32 people mainly from three teams. That's the largest single class I've had. For one reason or another (many of them were embedded systems developers, for example) the first day the whole class participation had some skepticism and generally was just quiet. (The small group break-out discussions were lively.)
I went home concerned that first day. Fortunately the remaining days were primarily full of activities. The whole class discussions were more typically lively in spite of the class size.
And now here's the point of this post. I found an interesting on-line tool, Electronic XPlorations, which turned out to be a great device on the last day of the second class. I wanted the class to talk to each other in review. This tool is a simple Java applet for four teams playing "problem" cards and applying "solution cards" and "value cards" to collect points. (I hoped, intended, and realized the goal of making the awarding of points fun rather than competitive.)
The great aspect of the game is that for a team to win points, they must explain the play they're making to the other teams. The others may challenge the explanation, and eventually accept or deny it.