Reddit mentions of The Little Book of Whittling: Passing Time on the Trail, on the Porch, and Under the Stars (Woodcarving Illustrated Books) (Fox Chapel Publishing) Instructions for 18 Down-Home Style Projects

The most important thing you can do is keep him engaged! Do fun things. If he hasn't got a pocket knife yet, he'll need one. 10yo is plenty old enough, as long as you teach him knife safety.

When he's got a knife, teach him to whittle. I bought The Little Book Of Whittling for my son and it kept him entertained for hours at a time. The book recommends good knives for kids, IIRC, so maybe get the book first if he doesn't have a knife yet.

So.....now, some projects that will keep him engaged.

• Make a slingshot
  
  
• Learn how to properly build a fire (not just randomly throw sticks into a pile). The key, obviously, is to stress SUPERVISION and SAFETY (this isn't something he can do without an adult present).
  
  
• Learn knots
  
  
• Learn how to use an axe (again, safety and supervision).
  
  
• Identify plants, like Poison Ivy or different trees
  
  
• Put together a small pocket fishing kit and use a stick as a fishing pole. Bluegill will eat just about any fly, and they're a blast to catch. Catching a bluegill will keep him engaged.
  
  
• Geocaching! I haven't done it, myself, but I've heard that recommended as a good introduction to the outdoors.

I started out with those knives (am still using them) and this book, which I found helpful because I didn't know where to start and it went through the very basics.