Still wondering how you can use a backchannel in the classroom?
How about the next time your students perform a presentation, the student audience has the backchannel running and focused on reviewing the topic of the presenter. At the end of the presentation the presenter can get great feedback from their peers. The audience stay engaged in the presentation and get more insight into what makes a presentation great.
Another one? A backchannel is a great place for other students to perform fact checking on the topics presented. The audience can do perform the fact checking and provide the links in the backchannel to support or refute the facts presented.
In general it's best to keep the backchannel focused on the classroom topic, multitasking is really hard for students, but when they are focusing on the same topic in the backchannel as the classroom, the focus transfers quite easily and naturally.