Sit the little blighters down and give them some actual case histories. Include some, not all, with bad outcomes.

The reason I suggest this is that it worked for me, back when I was young and clueless (big advance now - I am old and clueless). When I became interested in mountaineering, I started reading, and it became obvious that unanticipated bivouacs and accidents were part of the game. It gradually occurred to me that a certain amount of preparation could indeed come in handy. And later on, it did - in spades.

Still later, it was very evident that the common characteristic of nearly all our accident victims was inexperience - they simply had no apprehension of the hazards and the necessary defensive measures appropriate to the outdoor environment.

Go through the kits and role play - demonstrate the utility of what you are requiring them to carry.

You might also present a "Hug a Tree" session. This is a program that has effectively aided young kids in the outdoors. You might also get a presentation from your local SAR group; I'll bet they would be willing.