My school forbids cell phone use for students during the school day (except during lunch for high school) and thus last year I had to deal with kids trying to read novels under their desks/textbooks surreptitiously during class. It was kinda charming. Even their distractions were literacy-improving!
They often are! I did most of my teaching with at-risk kids, & if you really looked at the things they spent their time on, even the most traumatized were trying to educate themselves in one way or another.
I always feel a little bad about telling a kid they can't do homework for a different class during my class. There's good reason for it, and good reason for my consistency there, but it's such a laudable form of ignoring my class.
& also revealing about the kids' stresses around time management & overwork.