Asking 250 students to post questions on Twitter during a class doesn't risk life or limb. But it can cause ego damage if students get disorderly online. Opening up a Twitter-powered channel in class--which professors at other universities are experimenting with as well--alters classroom power dynamics and signals to students that they're in control. Fans of the approach applaud technology that promises to change professors' role from "sage on the stage" to "guide on the side." Those phrases are familiar to education reformers, who have long argued that education must be more interactive to hold the interest of today's students. The unanswered question, though, is whether that theory can work in practice. That uncertainty actually excites daredevil professors attempting this teaching trick. Many colleagues are watching such experiments with a mix of curiosity and disbelief to see how the professors land. The experiments went pretty well (no real disasters), but setting up a back channel is not for every professor, or every course. Students seem to love the chance to make their voices heard in class without having to actually speak. Instructors in the classroom, however, really have to teach toward their personalities because some say this would make them uncomfortable.