I just want to say THANK YOU. This site was amazing. I'm a 25-year-old trying to pick up where I left off. I had only up to 5th grade completed because my mom had pulled me out of school and homeschooled me. It was okay. She gave me the very basics that the state would allow (because she was lazy) and just said she was training us for "life". If it was not for this site I would not be able to get my GED so I can go to college to be a nurse like I want. I was able to go back and learn math skills that I did not have and I needed.
The one recommendation I would make about your test prep section is that it would be nice to have just a GED section for those that are trying to get one. It would make it simple to find exactly what you need for the GED instead of having to go through different grades or courses that make up for everything you need to know.
Thanks again Khan Academy <3. You guys are a life saver.