Professor Raj Persaud is a consultant psychiatrist at the Maudsley hospital and senior lecturer at the Institute of Psychiatry in London
"If you have no negative consequences for undesirable behaviour then you are doomed; that is a fundamental law of human behaviour. And those consequences must be applied consistently and made absolutely clear.
"The problem with talking is that teachers tend to let a hubbub rise in class to the point where they can no longer tolerate it before they do something, and then it's more difficult to claw things back. Background talking is difficult to define. If you are feeling benign, you'll be able to tolerate louder levels of talking than if you're tired. Be clear: zero tolerance of talking out of turn is the clearest observable definition and the one I would advocate.
"Children talk because they're bored, because they're not motivated by the subject or because they're seeking attention. Even the mouthiest child will be silent if they're watching a film they like. So, motivating them, interesting them in the subject, has to go hand in hand with zero tolerance. Upfront motivational analysis can be useful, such as getting them to look to the future to what they want to be - do they want to flip burgers or do they want to do something more interesting? - and showing how your subject can link in with their desires."
Professor Persaud will hold an online behaviour clinic at www.tes.co.uk on November 3