A quarter of a century ago, barely half the children of primary school age in sub-Saharan Africa were enrolled in school. By 2012 the share was 78 percent. In South Asia, primary school enrollment jumped to 94 percent from 75 percent over the same period. This didn’t happen by chance. Policy makers around the world have come to understand the importance of learning for every aspect of human development. Universal primary education was one of the United Nations’ core Millennium Development Goals, which mobilized large amounts of aid in the first decade of the century for poor countries to expand...
