It seems to me the Raspberry Pi people have put out a lot of good work making hard things possible and transforming education.

The video you posted reminded me about some of the work of Bret Victor, especially his interactive environments in his video on "inventing on principle". Although what's missing there is the ability to connect and modify the environment itself.

I still have to think a bit more about your link to Montessori, who has been a great inspiration for the school ( http://aventurijn.org ) that my parents started. Also in relation to what you said about teaching real math. Montessori has this system with beads and other countable cubes and pies to teach things like multiplying fractions, that is not used in most schools that call themselves "Montessori schools".