When Stanford professors Sebastian Thrun and Peter Norvig opened their Introduction to Artificial Intelligence course to the public in the fall of 2011, roughly 160,000 students from more than 190 countries signed up. The official course archive records that the class ran “from October 10th to December 18th 2011” and gave online students the same homework and exams as the on-campus section. The enrollment figure, far beyond any conventional lecture hall, is the number most often cited as the start of the modern MOOC era and led directly to the founding of Udacity.