Although it may not be possible to keep an eye on every student while you're teaching, by making small changes to your positioning in the classroom as you respond to individual questions or visit different tables, you can have a much wider view of the class which allows you to spot any misbehaviour or 'silent discos', as Adam Lewis puts it.

One of the first bits of advice I received regarding my behaviour management was to set-up my teaching radar.

This made me initially think there was some kind of device which could be set-up in the classroom to, firstly, detect where students were when my back was turned and, secondly, hopefully nuke the ones who were engaging in off-task behaviour.

It was soon explained to me that it was the art of knowing where your students were and what they were up to at all times. But the problem was that there was no device for this; it relied on your skill as a teacher.