Sugata Mitra works at NIIT, an Indian educational-software company. NIIT’s headquarters in Delhi borders the Kalkaji slum, and the two worlds are divided by a simple wall. Ten years ago, Mitra came up with the idea of putting a hole in the wall, and installing a computer in it, with an Internet connection. It soon became clear that children who had never seen or operated a computer could figure out all on their own how to surf the Net.