“Developing countries spend hundreds of billions of dollars each year on schools, educational materials and teachers, but relatively little is known about how effective these expenditures are at increasing students’ years of completed schooling and, more importantly, the skills that they learn while in school. This paper examines studies published between 1990 and 2010, in both the education literature and the economics literature, to investigate which specific school and teacher characteristics, if any, appear to have strong positive impacts on learning and time in school. Starting with over 9,000 studies, 79 are selected as being of sufficient quality.”

That is from the abstract of a working paper titled, “School Resources and Educational Outcomes in Developing Countries: A Review of the Literature from 1990 to 2010.” I haven’t finished reading the paper yet, but so far it is very interesting and quite comprehensive. Highly recommended if you work in education in developing countries.