MIT filmed a calculus course in black and white decades ago and it still teaches better than most of what shipped this year. Almost nobody watches it.
This is Calculus Revisited, Unit 1, Lecture 1, taught by Herb Gross. Analytic geometry from the ground up, chalk on a board, 1 camera locked in place.
Gross built the course for adults returning to math after years away. No prerequisites assumed. Every idea earned in front of you instead of quoted from a textbook.
The opening move is simple division written on the board. From there he shows why coordinates work at all, the thing most courses skip and every student silently fakes.
Watch how slowly he goes. Each step spoken out loud, nothing left implicit, the pace of someone who expects you to actually follow.
A backend engineer I know rewatched Unit 1 twice before touching linear algebra and said it fixed a gap he'd carried for 12 years.
MIT put the whole course online free under Creative Commons.
Production value aged badly. The teaching didn't.