I'm a big fan of Processing or p5.js for teaching kids that age how to write code. The immediate visual feedback from a line or two of code creates a positive feedback loop that encourages learning. Shiffman's book Learning Processing is a great gentle introduction: https://www.amazon.com/Learning-Processing-Second-Programmin... (https://www.amazon.com/Learning-Processing-Second-Programming-Interaction/dp/0123944430/ref=sr_1_3?s=books&ie=UTF8&qid=1469470998&sr=1-3&keywords=nature+of+code) His Nature of Code work -- simulating nature through code -- also is really interesting but requires a little background in coding.
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