Today I had a 7th grade math class (pre-algebra). After they did their warm-up and we had some time to discuss their homework (fractions), they had a review worksheet to complete.
Before I passed out the worksheet, I did my usual announcement to the class: "Do not write on this worksheet. This is a class set. Do your work on a separate sheet of paper..." I reiterate this a couple times, just to make sure that they heard me.
So, of course half the class starts writing on the worksheet.
It's like they didn't hear me. They look at me like it's my fault that they weren't paying attention. (These are the same kids who are surprised that there's a sub in the room even though the teacher told them that she was going to be out.)
Of course, it doesn't help that they had an assembly this morning. They were wound up all day.