Hey everyone! I really like how websites like Brilliant try to teach in an interactive way. But it's like $160 (or more depending on the region) a year so I've been making a free one.

It's called OpenAha. right now there's 140+ courses and 1000+ lessons in math, physics and chemistry. no account or ads.

A few to try if you only have a minute:

• untangle a graph: https://openaha.org/courses/graphs/planar/?step=1
• draw the house in one stroke: https://openaha.org/courses/graphs/konigsberg/?step=3
• program a little robot: https://openaha.org/courses/coding/sequence/?step=6
• Two pendulums passing energy back and forth: https://openaha.org/courses/waves/coupled/?step=3

This project is mostly implemented with claude: I planned every course, then wrote the lessons with AI. so far only about one third of the pages have been carefully reviewed by a person. That's why I'd really like people to poke at it. If a lesson is confusing or sth's wrong, make a PR or hit the flag button in the lessons. Also feel free to contribute on github to make this even better.

code: https://github.com/open-aha/open-aha.github.io

Edit, to clear something up: OpenAha isn't affiliated with Brilliant and doesn't use any of their content. I don't even have a Brilliant account. Brilliant just uses the style of learning I liked (try things first, explanation after). every lesson was written for this project, and we're improving it as an open source community.

And yes it's not finished, there will be mistakes. That's what the flag button on every step is for, every report gets fixed in public on github