I didn't even consider demonstrating a 'live' Twitter learning arrangement. Twitter isn't really fun if you haven't built your own network yet. So, I limited myself to showing how you can use Twitter in your teaching without being a Twitter user yourself, and then moved on to paper-Twitter.
Yes, you read correctly. Paper-Twitter. Inspired by blog posts detailing paper blogs and paper Facebook, I created a paper-based Twitter simulation within the workshop. We created three "accounts": @rot (red), @gelb (yellow) and @weiss (white) were 3-4 students seated around one table. They had color-coded question cards that they could use to send messages to other groups - of course with a limit of 140 characters. Groups, in turn, could respond with their own response cards. The task: Find a way to teach your subject matter this way :-)
Yes, it's a bit silly, but it was fun, and it was a good way to demonstrate the "joyful anarchy" of the Twitter stream. With the students' permission, here's a nice example of a dialogue initiated by @white: