Metal pet tags make great backpack IDs
When my son started kindergarten, I wanted to put an ID on his backpack. The luggage tag I got him disappeared pretty quickly, but the next time I was in the pet store, I got an idea. I bought tokens for the pet tag etching machine, and created a tag with his name and street address on it, and added my cell phone number. The metal couplers used to attach a tag to a collar work really well to attach it to the zipper of a backpack (and help keep rough play and busy fingers from removing it). Now, I know that if my son gets lost, he has our address and my cell phone number on him (and we can make sure he always takes home his own backpack, too).