Me as a parent

Only works if no one in their school has the same brand.
You bought the little brat an iPhone 6? Good luck with your "hack".

Turn off the wifi and put data blocks on their devices

Whoa! Calm down there, Satan.

nope. i dunno about you but over the years i have accumulated like 12 chargers that all work with all my devices (except my kindle cuz its fickle) odds are they have 2 or 3 more chargers hidden away. easier to take the device. even if they do not have a spare, a friend will lend them a charge.

All smartphones have the same mini usb chargers (except iPhone) but even if your child has an iPhone it can borrow chargers from classmates

YOU ARE A CRUEL HUMAN BEING. DON'T PUT THESE CRAZY IDEAS IN PEOPLES MINDS.

*To friend* Hey dude, my dad took my charger away can I charge my phone with yours please?