Khan Academy is a learning website founded when Salman Khan (aka Sal) had a granddaughter who was in a different state and needed help with math so Sal sent her videos to help her and then those videos went onto YouTube and they were big hits and a few years later Sal made Khan Academy.
Now in 2014 it's a HUGE hit there are 100's of 1000's of members on Khan Academy and there are >5000 videos and there are these things called skills that are basically tests to earn you these things called energy points that if you have enough energy points you can unlock avatars(they go in the front of your profile and they aren't one of those things that you buy the avatar and don't think how in the world am I going to get 250,000 energy points? because if you get a skill correctly done 5 questions in a row with no mistakes you get 600 energy points and 750 energy points for watching a video) and you can also earn badges that give you energy points and I'll leave the rest for you to explore on your own and here's our profiles:
https://www.khanacademy.org/profile/_kag5zfmtoYW4tYWNhZGVteXJPCxIIVXNlckRhdGEiQXVzZXJfaWRfa2V5X2h0dHA6Ly9nb29nbGVpZC5raGFuYWNhZGVteS5vcmcvMTE4MDk0NzU4MzkxNzg4OTkzMzgxDA/
Jeremiah's profile(the 7 year old)
https://www.khanacademy.org/profile/Pickleboys/
My profile(the 10 year old)