For two years, the authors researched the work of thirteen schools in the lower income sectors of Santiago that had high, moderate and low scores on the national educational quality test (Simce), the purpose being to identify which factors inside the school might explain the differences in scores. Instead of addressing many dimensions, they concentrated on how reading is learned since it is a foundation of learning. They controlled the socioeconomic factor through the sample design and found that schools that performed differently clearly differed in reading achievements in the early years, in the quantity of classroom work, in pedagogical management variables and in the view that school authorities have of education. There are schools that are organized to provide more and better opportunities to learn and others that lack the organizational and pedagogical competencies for children to attain the minimum knowledge and skills that can be expected. The study concludes that what teachers do in the classroom is what most affects how students progress and that an appropriate pedagogical management leads to dedicated and effective teaching by teachers. Here we reproduce the introductory chapter and the conclusions from this research.