This five-minute video gives an impression of what it is like using Twitter as a backchannel in a large classroom.

I am already a HUGE fan of Twitter as a tool for extending my PLN. Logistically, I'm unsure how tweet-ing would work in a NSW high school context at the moment (leaving aside the fact that it is blocked by the web filter) - can anyone out there share a success story?

I love the instructor's willingness to "try something messy!" Nice use of Twitter in the classroom.