This is for your advanced young hobbyist, not your sneak-a-fold-in-the-classroom tyke.
My 6 year-old son loves making paper airplanes but didn't really understand how to do it correctly. He and his dad really enjoy this book and making the airplanes in it. I like how there is special paper, each with specific directions so he can make the same airplane as pictured in the book. Each paper also comes with several copies so he can perfect the method.