In many parts of the world, we have created a learning crisis: more kids are in school, but they are not learning. “We are failing the children on a massive scale,” says celebrated development economist Esther Duflo, John Bates Clark Medal winner and author of Poor Economics. “There has been improvement in enrolment and in the physical capacity of schools. But learning is not about enrolment, teacher-student ratio, having latrines in school; it’s about if we are serious about learning.”

In September, world leaders will get together and agree that improving the quality of education should be one of the Sustainable Development Goals that replace the MDGs. Something must be done, they will say. But what?