This is another technique presented by Doug Lemov in his collection of methods for classroom discipline that, to my mind, resonates strongly with his techniques for actual teaching. It’s quite simple, but very powerful: if you want someone to do something, tell them exactly what actions they need to take.
To elaborate: quite often if children (well, people) fail to follow an instruction, it’s not that they’re being deliberately obstructive, merely incompetent. An instruction such as ‘Behave yourself!’ is ambiguous; it tells the child they’re doing something wrong, but doesn’t state what’s actually required. Even the more specific, ‘Stop fidgeting!’ only makes it clear what’s wrong, not how to fix it.
‘Please sit down and face this way,’ gives a nice clear to-do list, and even a child who is in something of a bolshy mood might find it easier to just to get on with it than continue to resist in the face of such calm clarity.