Deficiencies in student learning within the developing world have been attributed to a number of factors, including high student-teacher ratios and a dearth of resources in public schools. While these arguments seem plausible, several studies suggest that simply increasing educational inputs—such as books and other learning materials—is not enough to improve  learning outcomes. One study in Kenya found that providing more textbooks to students had little impact on student performance—unless students were already top performers. Another Kenya-based study suggested that providing flip charts to schools was unlikely to positively influence test scores.

However, rigorous research by the Abdul Latif Jameel Poverty Action Lab (J-PAL) has offered at least one clear reason why children are not learning. It has to do with how classes are organized. Typically, students are clustered into age-based learning groups and taught from a standardized curriculum. All children who are six, for instance, are usually placed in first grade and taken through the prescribed content for their grade level before advancing to the next grade level, and they advance irrespective of whether they have achieved proficiency in the previous grade’s content. This formulation assumes that students of the same age generally start from the same baseline of skills and knowledge, and can therefore learn the same content at more or less the same pace; which, research shows, is not the case. In reality, the reverse is true: any given classroom consists of students operating at very disparate levels of competency. In a typical 8th grade class, for instance, students may operating at 3rd, 4th, 5th, 6th and 7th grade competencies. Grouping these children together simply on the basis of their age limits the attention that can be given to each learner’s unique needs. That’s especially true when teachers are obligated to cover a prescribed amount of content within a defined period of time. The result is that as curricula move forward, stronger students keep pace while struggling learners get left behind and, potentially, never catch up.