What is the aim of public education?

I thought that this answer from Esther Duflo, this year's Jon Clark Bates Medal winner and co-author, with Abhijit Banerjee, of Poor Economics was really interesting and thought-provoking:

Q. Yes, you argue that the research shows all children — including ill-prepared ones — can learn and that even modest differences in outcomes — say, finishing fifth grade instead of second grade — have positive effects. But obviously many, many schools, from Mumbai to Lagos to Houston, do a bad job of educating poor children. What distinguishes the schools that get impressive (and rigorously evaluated) results?

Ms. Duflo: That’s indeed a vexing puzzle: experiences in the developing countries (the very successful remedial education programs run by Pratham, in India, for example) but also in the U.S. (the “no excuses” charter schools in Boston, or schools in the Harlem Child Zone in New York City) suggest that it is possible, perhaps even not that difficult, to significantly improve the quality of education. Yet most schools completely fail their students: why is that? It would be too easy to blame a lackadaisical public school system, but even the private schools that are attended by many poor kids around the world could do much better. In the U.S., not all charter schools deliver quality education.

Our sense is that what is going on is that schools have forgotten, or perhaps never knew, that teaching fundamental skills to everyone should be their prime objective. In Kenya, India or Ghana, teachers still try to teach an absurdly demanding curriculum to a very diverse set of pupils, many of whom are first-generation literates and get little or no help at home. Covering the entire curriculum is the priority, even though the majority of children may be lost by the end of the first week.

Why aren’t parents revolting, one might wonder. Why are they not demanding that their children be taught at the appropriate level, instead of sitting through day after day of teaching that mean nothing to them? In part this is because they do not know how badly schools are doing: they are not in a position to evaluate what their children are learning, and no one tells them that they are not. In part it is because they have bought into the elite bias that plagues the entire system: parents often seem to believe that education is worth it only if the child can reach the highest level.

Making sure that schools deliver may be in part a matter of defining what “deliver” means: not preparing the top of the class for some difficult public exam while ignoring the rest, but ensuring that every child learns core skills, and learns them well.