The Value-Added of the Khan World School Test

The Khan World School students took a test called exact path, which is used by about 8000 school districts nationwide. The typical American ninth grader on this test sees his or her math scores go up by 19 points on average over the course of ninth grade. At Khan World School, the average increase in scores was more than four times the gains of a typical student. It's weird because the broader education establishment would cut off their left arm for 4%. We're talking about 400% improvement.