Since the 2001 passage of the No Child Left Behind Act (NCLB), test-based accountability has been an organizing principle--perhaps "the" organizing principle--of efforts to improve American schools. But lately, accountability has been under fire from many critics, including Common Core opponents and those calling for more multifaceted…

This article features Khan Academy which offers an online math program and short video lectures embedded in the "module", or math concept, that fit students' goals. By now, more than 1 million people have watched the online video in which Salman Khan--a charming MIT math whiz, Harvard Business School graduate, and former Boston hedge-fund…