Khan Academy Interface

Khan Academy has been offering free education online since 2008. An interesting design choice is how little the interface has changed in that time relative to how much the content has expanded. Courses are organized as a skill tree where each topic branches into sub-topics and each sub-topic breaks down into lessons with practice exercises. The visual metaphor of a branching tree makes the structure of a subject legible unlike a flat list of videos. Progress tracking uses a mastery system where you have to answer 5 questions correctly in a row before advancing, preventing the common problem of passive video watching without retention. A recent redesign added a cleaner layout and a more modern color palette, but the fundamental structure of short videos followed by interactive practice remained untouched because it works. Simplicity of the model, 1 teacher explaining 1 concept at a whiteboard, scales to millions of learners precisely because it asks nothing of the viewer except attention and willingness to try the exercises afterward. I used Khan Academy to catch up on statistics before this semester. Explanation quality is consistently better than most of the recorded lectures available through my university.