This may be a different idea to "doing nothing", but when I teach labs, I explicitly do not get on the computer while students are working. Instead, I literally

This may be a different idea to "doing nothing", but when I teach labs, I explicitly do not get on the computer while students are working. Instead, I literally just stand there looking for students to ask me questions. I've noticed that whenever I would start working on grades, or assignments, or whatever, students would never ask for help unless it was dire. When I was at attention, while it wasn't constant, I found myself helping students more. Over time, I've assumed it is because they don't want to "bother" me or break my concentration. However, when all I am doing is waiting for them to ask a question, I seemed to get more activity.