Scratch and Algebra
Scratch and Geometry
For more Geometry, see Dan Anderson’s Geometry from Scratch presentation at the 2016 NCTM Annual Meeting.
Scratch and Simulation
You can find more examples at my NCTM 2017 Scratch Studio.
The book Mindstorms, by Seymour Papert, lays the philosophical groundwork for teaching mathematics through programming in LOGO, the progenitor of Scratch. The book is freely available at the MIT website here.
Feel free to contact me with any further questions. And please let me know if you end up trying Scratch out in your math classroom!