At Teachers Training College it is emphasised that you must be fair to all students and be seen to be fair. Students when asked tell you the same thing ” Be fair, don’t have favourites”.
I have found that a big red dice is useful as a means of being seen to be fair.
When asking a question to a resounding silence (or the same students) I sometimes get a student to roll dice as a means of randomly selecting a student to answer a question (or ask one). That students reward is they then get to roll the dice for the next “happy” volunteer.
It’s also lots of fun.