His GPS unit had a problem with gravity and a rock, and he texted to let me know fortunately he's good with a compass and landmarks and a topo map (I'd like to take credit for teaching him that but I think he was self-taught).
Sometimes it's good to have the Simple Tools around, for when the complex ones break; I sent him a list of my favorites, and their modern not-too-complex versions:
1. Rock --> Hammer
2. Stick --> Club/ rybar
3. Knife --> Axe
4. String --> Rope
5. Wheel --> Pulley
6. Spark/fuel --> Fire
7. Fire/stick --> Charcoal/Pencil
8. Stick/string/pulley-that-flings-Knife --> Bow & Arrow
9. Stick/fire-that-flings-Rock --> Gun
Beyond those, reliability starts to go downhill....
