Help them figure out triangle bandaging, splinting, and pulse rates. Setting up a bush hospital can be a blast for kids. First aid is never a game. Back in camp, the possibilities are manifold. There are routine chores and the tribal stuff.
Kids can collect kindling, drag in wood, and saw it.
They need to create, control, use, and put out a fire. Teach them to build a one-match fire and to boil water in a metal cup, on coals, to make it potable in unsafe water areas. Fire lighting and maintenance is a deep human need that kids have to satisfy. Let them demystify fire and replace the pyromaniac urge with respectful fire tending. With limited criteria on ground types, wind direction, and views, they can select great tent and fire sites.