Now that cell phones are creeping down into the lower grades, think about this too: my kid (until we talked about it) kept her wallet & cell phone in her backpack. Great!  So if she needs to call for help she has to stop and fumble in the pack. Or maybe she dumped the pack to run away so she doesn’t have the phone with her.  :-((  So now I tell my girls to keep their cell phones and wallets in their pockets so they can dump the backpack and still have the minimum stuff they need.