Khan Academy

Khan Academy is a non-profit educational organization. It has been created by Sal Khan. Khan Academy is available on the internet for free. Khan Academy teaches by using YouTube videos of short lectures of certain topics, as well as by using practice exercises and tools that help with learning. It is available in many different languages, but mostly English.
Khan Academy teaches mostly about mathematics, but also teaches biology, chemistry, physics, history, astronomy, cosmology, American civics, art history, economics, music, computer programming and computer science, healthcare, medicine, and finance. In the YouTube videos that Khan Academy makes, they record diagrams being drawn from a tablet using the screen capture software called Camtasia Studio.