From Technology Review: The wave of enthusiasm for online education is unearthing some hard and interesting computational problems that Daphne Koller would love to solve. Last January, Koller and her colleague Andrew Ng took leave from faculty positions at Stanford University’s artificial-intelligence lab to create Coursera, a venture-financed online-education startup with offices five miles from campus. Since then, Coursera’s growth has been rapid and all consuming. The company has posted more than 200 free classes taught by professors at 33 top universities, such as the University of Pennsylvania and Caltech. More than 1.5 million students have signed up, and about 70,000 new students—the equivalent of four or five Stanfords—join every week.