Scott… when I was a pre-teen I took a 4-H Outdoor Living course. I had wanted to be in Girl Guides but there wasn't anything available in our rural community. Anyway, the reason I am telling you this, is the learning from that course is still with me.
We made all sorts of things and learned all the basics of camping. What we also learned was how to dry foods. As you can see from my profile this has stuck with me into adulthood and now it's part of my day job. While it is something you could do, it is a time consuming effort.
What about making your own energy bars as a group. I have a recipe that is perfect for this. I'm unsure how many children you have in your group but they could be grouped into smaller units and make these bars. The nice thing is that the bars can be customized just like GORP and it makes it really fun to pick out the ingredients and make them. It is a no-bake recipe and works great.
I also have an instant Moosey Mousse Mix recipe that the kids could package up for their trip. It's a fun project and practical because it is part of their menu. I have a bunch of materials that I've written (both for my book and classes) that you are welcome to when it comes to food.
I also have a pattern for a UL Checker game that can be made with a bandanna and some things like that which may be of use to you.
Speaking of bandannas, we did a little game in the 4-H thing about uses for them in the backcountry. Part of the game was serious but some of it was quite silly.
Another thing you can do is teach them about animal tracks. We did this for the younger kids in a workshop I was teaching and we made tracks out of construction paper and put them on the floor… then the kids played a little game to learn what they are. The older kids helped set it up. We kept the tracks appropriate to what they might see in the area.
We usually got the kids in the workshops to build a mini-personal first aid kit for their pack and talked about how to handle more serious emergencies.
There are so many things you can do. I'd only recommend building the stove with the oldest of the kids because it is quite easy for the younger ones to cut themselves and the younger they are – the shorter their attention span.
Feel free to email me through the PM system here and I can pass along some of my materials to you.