The Global Learning XPrize competition is looking at ways in which children can teach themselves reading, writing and mathematics with only a tablet computer. The XPrize Foundation and its supporters are offering $15 million for computer programs that teach simple skills to people who have never attended school. Matt Keller is senior director of the competition. He described the goal of the prize this way: “It’s a little bit out there. It’s a little bit of a crazy idea.” The first Global XPrize competition is awarding millions of dollars to the team or company that develops the best educational app. The United Nations Educational, Scientific and Cultural Organization, or UNESCO, estimates that 263 million children around the world are not in school.