All of those problems can be solved without smartphones, as evidenced by literally every previous generation dealing with them. If anything, my grumpy self would argue that not having means to contact my parents if I forgot something ensured that I paid more attention the night before to what I had to pack.
But I'm open to compromise: let's give children bring dumb phones that can only call and text.
Sure. I remember standing in line at the phone for 10 minutes as a kid waiting for my turn to call my parents when my activity was done. Cell phones are better. Smart phones would mean I could use the time waiting for something.
Smart phones when class is in session is a distraction and should be banned. However outside of class they are helpful.
But I'm open to compromise: let's give children bring dumb phones that can only call and text.