For me it was this curriculum, which should be better-known: https://www.elementsofmathematics.com/ https://www.elementsofmathematics.com/ One place it is offe

For me it was this curriculum, which should be better-known: https://www.elementsofmathematics.com/ https://www.elementsofmathematics.com/ One place it is offered in-person is the St. Louis area where I grew up: https://megsss.org/about-us/ https://megsss.org/about-us/