As a teacher here's my two cents.
Some of you have hit the nail right on the hit. Far too many parents are using electronic devices like smart phones and game systems as babysitters. They either don't want to or simply don't have the time to play with their kids and teach them how to entertain themselves with imaginative play. It's much easier to buy them a new video game to keep them out of your hair while you do other things.
And then the kids come to school where they are expected to sit quietly, concentrate on learning, and actually read something from a book. And many of them simply can't because those traits (along with delaying gratification) have never been taught (or modeled) at home.
Now, it's not every kid, but it's an increasing percentage of them. Right now I'd put it at 20%.
But the numbers are increasing each and every year.
This is the first generation of kids to be wired in almost from birth. There are going to be societal implications that we simply aren't ready to deal with.
And wait until these kids start having kids.
Of course, by then, I'll be retired from the profession. And I'll be thanking God for that!