"They also spend significant time building their own games. Sometimes they design board games using cardboard and markers and ungodly amounts of tape. Most of the time, though, they invent games for the computer. Salen’s theory goes like this: building a game — even the kind of simple game a sixth grader might build — is equivalent to building a miniworld, a dynamic system governed by a set of rules, complete with challenges, obstacles and goals. At its best, game design can be an interdisciplinary exercise involving math, writing, art, computer programming, deductive reasoning and critical thinking skills. If children can build, play and understand games that work, it’s possible that someday they will understand and design systems that work. And the world is full of complicated systems."