I was going to let my oldest son take the one that's just the engine, apart so he could learn how they tick. When I was his age I didn't ask. I took everything apart to see what made them tick much to my moms dismay. Kids don't have that sense of curiousity anymore. I never lost it. Thank god. My youngest shows promise if he doesn't burn the house down. Obcessed with fire as he should be.