SuperGus writes: I have a 5 year old who, much to my delight, is turning into quite the curious little hacker. He likes the mechanical stuff — bikes, cars, telescopes — and happily tinkers with my tools. However, he's gotten very curious about electronics, like our home-brew PCs. As a mechanical engineer I learned by analogy to physical systems, so I imagine playing with springs, dampers, and rubber bands before attempting capacitors, resistors, and batteries. In a few years I'm sure we'll have fun programming (Lego Mindstorm?) but for now I'd like to help him grasp how stuff works at the physical level. How best to help him explore electronics — stick with mechanical concepts first? Turn him loose on a simple electronics DIY kit now?