Use chapter six of Horace Kephart's Camping and Woodcraft to guide them. Aboriginal trackers, Polynesian seafarers, and Inuit hunters used the land, sky, and water to tell time, direction, and distance. Start with compass bearings of a mountain, the sun, a tree, or the Pole star. Walk a compass line, taking readings. Record exactly where the sun rises and sets in the physical geography, according to both the sticks and the compass.
Details add spice.
Go through the mechanics of signaling with a tarp, a hand mirror, a signal mirror, and a smoky fire. Suggest alternative ways, like anchoring a canoe out in the water, to be visible. Let them come up with and test other ways to be found by searchers. Supply kids with primer plant and animal guides and use binoculars for distance IDs and a small hand lens for close inspection of leaf veins, flower corolla cavities, and rock complexions, for bark, feathers, and insect bodies, and for human irises, nails, and skin. Let them go into excruciating detail and add another sketch or feathers to the log book.