Programmable robot swarms. https://wyss.harvard.edu/technology/programmable-robot-swarms/ https://wyss.harvard.edu/technology/programmable-robot-swarm... I do

Programmable robot swarms. https://wyss.harvard.edu/technology/programmable-robot-swarms/ https://wyss.harvard.edu/technology/programmable-robot-swarm... I don't know how affordable the hardware would be for a hobbyist, but this would be so awesome for a kid. Ten little autonomous metal insects, roving around on the floor. The programming side has a lot of visually-intuitive aspects, such as pathfinding; show a child a graphical display of a robot's pathfinding algorithm and they will just "get it." And how cool would it sound to have all those little motors alive in the classroom? You could parlay it into a discussion about drones (one of your passions), and show them clips from e.g. the Superbowl, where coordinated drones with LEDs created an animated backdrop for the performance. For bonus points, you could use genetic programming to evolve some kind of group behavior, then execute the variously-successful generations, and show them how the most evolved algorithms seem the most alive.