I've been working through Nand2Tetris with my 13-year-old son, but the official hardware simulator was pretty overwhelming. That's why I built a browser version that tests the first 2 chapters, is simpler, and has a tighter feedback loop with more helpful hints.
Let me know what you think, especially if you are young or teaching young people. If you have any feedback, open an issue here or comment below: https://github.com/jaysonvirissimo/build-your-own-alu.