Just something that came to mind reading this great comment, have you considered using webcam + canvas manipulation for that great block of fun Javascript? I've been doing Javascript30 (https://javascript30.com/), and day 19 (unreal webcam fun) he showed doing live image filters with simple pixel manipulation on a canvas populated by the user's webcam - it was awesome, I think kids would love it, and it lends itself really nicely to your model of a pile of variables to play with and break. That course is free (no affiliation but it's awesome!) and all the code is on Github, the webcam one is here: https://github.com/wesbos/JavaScript30/tree/master/19%20-%20...