But probably not to their parents or teachers for that very reason

And if parents are paying for it, then it might not be dead to students at all. They may have to have that rather than something that allows them to check out facebook and chat rather than paying attention to the lecture and taking notes.
I can say, as a teacher, that *I* would much rather students have an iPad limiting them to note taking then knowing that they're chatting, etc. while I'm lecturing.

It's childish, disrespectful, stupid, and proves that you really don't deserve to be there--so don't expect any sympathy for me at your "boo-hoo! It doesn't multitask!" Oh, poor baby, can't go on facebook during class!

So far as I'm concerned, you shouldn't be wasting the teacher's time or yours or your parents money by doing such things.