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...

His Nature of Code work -- simulating nature through code -- also is really interesting but requires a little background in coding.