As it happens, yesterday I walked in on my younger daughter, who was working on a program written in what looked like MIT's Scratch at [code.org](https://code.org/). Digging around, I find it was actually [Blockly](https://en.wikipedia.org/wiki/Blockly).
[Here's a link](https://drive.google.com/file/d/1hdLc9nZzTnBDcN9qJeDlJm1F9IL91Lvi/view) to the Ada book I mentioned. It attributes its inspiration to a C++ book. Just offering resources if you want to see what people have been doing to teach programming to 12- and 13-year olds.
