I have got a filing cabinet near my classroom door. On top of it I have a 3-tier filing tray with paper in. No problem for my my classes - except one. This one year 9 class have a trick of at the end of the lesson on their way out one of them reaches back in through the door and pushes these trays with all their contents across the room. Then they run away leaving all the mess for me to clear up before my next lesson. Today I had kept four behind so I was off my guard - but when I let these four go of course the same thing happened. Irritating but at least it narrows it down. No matter how long I am in teaching, I never quite know what to do in these circumstances. Should I:- - just do nothing (probably sensible but I know that this will just keep on happening now) -give up and move the trays (not much room though) - give them all a detention unless one of them owns up (dodgy I know) - speak to them individually to see if one will grass the culprit up (they haven't so far) I would love to know if any Tessers have a special way of investigating things like this - any tips?