This is adapted from a post I saw on HN years ago. Can't find a reference ATM, but the gist is: Use a simple goal oriented task - picking up a ball from one en

This is adapted from a post I saw on HN years ago. Can't find a reference ATM, but the gist is: Use a simple goal oriented task - picking up a ball from one end of the room and depositing it at the other end, navigating some obstacles (coffee table etc). You are the "robot" they are programming. Provide a partial "instruction set" left, right, forward (1-step). Let the child figure the algorithm to pick the object, navigate the obstacles and discover the rest of the instruction-set. They string together a program as a string of post-it notes. The only rules are the "robot" always runs the program from the beginning - no hot-patching. If the instructions bump you into a table, you stop. The child goes fixes the program, and you start over. Great for debugging skills and building abstractions in the head. Incredible, how quickly they discover loops and functions. And very quickly learn to create program in the abstract for other tasks (unloading a dish-washer). I never went as far as sorting lego bricks, but that might be another interesting direction to explore to introduce algorithms.