Four years ago Harvard Business School Professor Clayton Christensen predicted that online education would take off slowly and then hit everyone by surprise: the S-curve effect. And indeed, while it initially grew slowly, online education has exploded over the past several years. According to the 2010 Sloan Survey of Online Learning, approximately 5.6 million students took at least one web-based class during the fall 2009 semester, which marked a 21% growth from the previous year. That’s up from 45,000 in 2000 and experts predict that online education could reach 14 million in 2014.