Being a former scout and scout leader myself I can say that most younger/new scouts would run into the woods naked if they could. It's hard to get them to even carry water, never mind anything else. Most of them are used to handing something off to their parents to carry and going off to have fun. It's tough to get them to remember to take their supplies with them. We started by giving them a whistle and a little knock-off photon light on a chain and we would do random checks to make sure they have it at meetings and on trips. In the first meetings we would go over what to do if lost in the woods and the proper way to use the whistle. Later on you can move to things like water bottles, small first aid/survival kits, ect. Each meeting you cover something new, like going over why proper hydration is important and work on first aid skills for dehydration. After that all the kids need to have their whistle/photon and water bottle on trips. Eventually they get it down, but you need to keep at it with them. Lots of practice.

Now, when I started teaching my younger brother how to do wilderness survival I bought him one of those small hydration back packs, the ones made for bicycling. I made up a small survival/first aid kit in a ziplock bag and stuck that in there. I would then take him out on a short hike in the woods by our house with a stop to work on skills. Worked great since it was light enough for him to carry easily, kept at least the bare minimum of gear within reach, and since his water was connected to his pack he would never forget his kit if he remembered to take his water (which I would remind him about, and I we got into the habit of both filling our camelbaks at the same time before we left)