File this under low-tech toys for nascent nerds. My grandfather had a penchant for small puzzles and games. Whenever I visited, there would be a small collection on a side table near the fireplace just asking to be played with. I can't make any grandiose claims about their educational value, but they definitely required a certain amount of analytical thinking to solve. Many of the puzzles migrated to our house as I asked to borrow them, or got my dad to make me a copy.
One of the ones I remember best was the towers of hanoi. It's nothing more complicated than a board with three pegs and a set of rings in a range of sizes. The puzzle is to move the entire stack from one post to another, moving only one ring at a time, and never placing a larger ring on a smaller one. The solution is not particularly difficult, but can become quite complex. With appropriate adult explanations, it can also be a demonstration of some important life lessons for the developing nerd, like computer arithmetic, and exponential growth. I feel that most of the hard problems we face as a society can be traced at least in part to insufficient understanding of exponentiation.
Something reminded me of the Towers of Hanoi the other day, and I was immediately determined that Little Pete (LP) needed to grow up in a house with one. I won't bore you with the fabrication details as its fairly obvious:one board, three pegs, bunch of rings. As with most projects, the final result isn't quite what I had in mind at the start. I was picturing an elegantly finished objet d'art that could take a proud place on any coffee table. Once assembly was complete, however I became daunted by the time it would take me to do it justice in the sanding and finishing department. It occurred to me that my fond memories had nothing to do with the fit and finish. Besides, with sufficient handling, bare wood can get a patina that's hard to replicate any other way.
I simply left it out on the end table as you see it here. It took LP about 20 seconds to zero in on it when he entered the room. He's not trying to solve the puzzles yet, but he's been experimenting with what patterns he can make stacking the rings. I think that has value too. He's imagining something, then putting it together, and evaluating its effect. I also just discovered that stacking them small to large is "an ice cream cone." It's not a complex toy, but sometimes the simple ones can provide the most opportunities for creativity.