When my teacher is off, I have a cover come in, as I insist that I am not going to be left on my own with a class, the particular students I work with can't handle change, so their behaviour can be a bit erratic.. Guess, who actually takes the class? Me, surprise! The cover just sits and does nothing. On the occassion that the cover has been on their own, with work left plus instructions, plus the students know what they have to do, nothing gets done. Might as well let the students go outside and kick a ball around.
I do feel that some of the covers employed in school get of very lightly.