I always put my classes in a seating plan. As much as anything it's about showing that you control what happens in your classroom. I'm not against reasonable requests for pupils to move places but it has to with my approval.
I was quite happy when one year nine came to me at the start of a lesson this week and asked if he could sit on his own. I told him there was an empty desk at the back he could have to himself if he liked.
A couple of moments later another boy asks why he's sat at the back. I explained that he'd requested to sit on his own.
'Oh I want to sit on my own too, can I sit next to him?'
menhir

There's a definition re-arrangement here.
