Hubble, Friedman, Guth. Learn all about the history of the universe through the lens of elementary cosmology. Topics to be covered include the cosmological distance ladder, scale factor, Friedman equation, curvature and non-euclidean geometries, the Lambda-cdm model, distance metrics, and more!

Build a fictional world together! There will be a map+docs where anyone can add details and features: make the world's history, geography, and cultures.

Have you ever wondered what the applications of abstract algebra to real world life are? Explore how groups can be used to solve a famous puzzle involving a game (the 15 puzzle) and more. [Edited]