I haven't had a chance to try React.js koans yet, but recently completed a tutorial in the same vein, a "workershopper", from nodeschool.io: <a href="https://github.com/tako-black/learnyoureact" rel="nofollow">https://github.com/tako-black/learnyoureact</a>. As a React.js noob, I found it to be a helpful introduction.