Nice TIME article that investigates several approaches. It starts with a pretty memorable hook:
On Sept. 17, the Pakistani government shut down access to YouTube. The purported reason was to block the anti-Muslim film trailer that was inciting protests around the world.
One little-noticed consequence of this decision was that 215 people in Pakistan suddenly lost their seats in a massive, open online physics course. The free college-level class, created by a Silicon Valley start-up called Udacity, included hundreds of short YouTube videos embedded on its website. Some 23,000 students worldwide had enrolled, including Khadijah Niazi, a pigtailed 11-year-old in Lahore. She was on question six of the final exam when she encountered a curt message saying “this site is unavailable.”