A few other comments! It would help to know the ages and capability of the kids. If they are to wear them around their necks that would call for a compact, lightweight kit. And what a SERE-trained airman might carry would require skills those kids probably don't have. Will the kids receive training, even rudimentary, on survival?

For premade kits, I think the SOL Scout Kit is a decent place to start. It's relatively small and would be easy to wear on a lanyard. There's a space blanket, whistle, mirror and a small fire kit among other things. None of the stuff would take a ton of training to use. The blanket is at least a bit of shelter and protection.