How can an instructor or teaching assistant encourage students to answers questions from other students posted in private Q&A online platforms dedicated to the classroom (e.g. Piazza), put aside from adding some percentage of the final grade based on such activities?
I used Piazza in my undergraduate business and society course last year. Students were required to participate, but I found that if I myself commented on some of their posts and then brought up some of their arguments in class that this encouraged more active posts. In particular I made a point of highlighting debates between students during subsequent class periods.