For a long time, math was for what Khan Academy was known. While programming is over taking that role, Khan Academy's roots will always be in clear videos explaining math concepts. Salman Khan color codes his concepts. Learning from a video provides the ability to pause and frantically try to work out the problem, then watch the problem be worked out. As users can see below, there is math for all ages and levels.
Math is also the only subject where student's progress appears in the drop down menu. When they doodle, math is often subconsciously at work. To find out how, students can try out the recreational math section.