Salman Khan’s educational website of 2,400 video lessons could
be the solution to middle-of-the-class mediocrity.  How Khan
Academy Is Changing the Rules of Education  Matthew Carpenter,
age 10, has completed 642 inverse trigonometry problems at
Photo: Joe Pugliese           Not everyone agrees. Critics argue
that Khan’s videos and software encourage uncreative, repetitive
drilling—and leave kids staring at screens instead of
interacting with real live teachers. Even Khan will acknowledge
that he’s not an educational professional; he’s just a nerd who
improvised a cool way to teach people things. And for better or
worse, this means that he doesn’t have a consistent,
comprehensive plan for overhauling school curricula.  Whatever
Khan’s limits, his site has become extremely popular. More than
2 million users watch his videos every month, and all told they
answer about 15 questions per second. Khan is clearly helping
students master difficult and vital subjects. And he’s not
alone: From TED talks to iTunes U to