Depends on if you know the material or not. If you do, then the teacher really can't say anything. But if it is new, and you don't know it, then yes, the teacher can nag at you.
For example, I haven't paid attention in my math class for the past week, I just sat at my desk and worked ahead because I got bored. We had the test on the chapter I didn't pay attention to today and I was the only one in the entire class who thought it was easy.
I agree with you. That's what I trying to say but did want to add it because I felt the post would be longer then it already is. But eduction is still important and requires focus. But for those days were you just want to sit back and relax.