Our interactive modules made up half of the Playing by the Rules exhibit at the Museum of Science, Boston, was a popular exhibit that explored how complex natural phenomenon can be based on simple rules. Three displays showed three different phenomenon that look sophisticated, but are really generated from very simple rules:fireflies blinking in synch, fads spreading through a city, and fish schooling. A more involved game let visitors impart any combination of six different movement rules to a population of birds, with the goal of getting the birds to flock, to nest, or to fly south for the winter in a line. Based on work at the Teacher Education Program at MIT, these interactives complemented the museum’s very popular Virtual Fish Tank and helped visitors see how some parts of nature may not be as complicated as they seem.