In October, 15,000 people had signed up for Alex Halderman's "Securing Digital Democracy," 25,000 for Silvio Savarese and Fei-Fei Li's "Computer Vision: From 3D Reconstruction to Visual Recognition," 57,000 for Lada Adamic's "Social Network Analysis," and nearly 92,000 for Scott Page's "Model Thinking." But unlike the brick-and-mortar students, most soon drop out. "It's hard to put a finger on 'enrolled,'" Adamic emails. "More than 57,000 people are registered [for his class], 12,000 watched all of week 1 lectures, and even fewer (6,000) submitted the first week's assignment."
[Originally published in November, 2012.]