Great post. And kudos to the groundbreaking work by Eben Upton and others in Cambridge, for giving the Raspberry PI to us so this kind of effort can now happen anywhere in the world at minimum cost.
PyTurtle is a great library for educational use - I used it to teach 11-year-olds in Scotland how to draw a house. The approach take was: instruct pupils to draw a house on paper, using only straight lines; teach them briefly what a coordinate system is (assigning numeric addresses - pairs of numbers - to points), which they haven't had in their maths curriculum at that stage, but which they easily picked up; translate the paper-based house into a sequence of PyTurtle Python commands.