Brilliant has a bunch of math courses, up into calculus and other high-level math. It also has some gamification with points and daily streaks for completing lessons

Totally different from Zero motorcycles

Minute Cryptic has a daily cryptic crossword clue which is pretty fun. And they post video explanations for each solution, which is helpful for learning how cryptic crosswords work

The country is Colombia, not Columbia

I’m reading a book “Because Internet” that talks about exactly this - how online writing evolves and can develop subtle meaning. It’s pretty interesting

I recently discovered Ben Eater, his videos about how computer hardware works are really interesting