Developing Textbooks to Improve Math Learning in Primary Education: Empirical Evidence from El Salvador

Although primary school enrollment in developing countries has rapidly increased since 1990, the quality of education has stagnated over the years. In teaching and learning practices, textbooks are an important intermediate that links curriculum, teachers, and students. Through a randomized controlled trial in El Salvador, this study evaluated the effect of a package of interventions including the distribution of textbooks that were carefully designed to improve math learning. This study targeted second-grade students and tracked them for 2 years. To capture their progress in learning over the period, this study linked math test scores at the end of the second grade and third grade by using the item response theory (IRT). The average 1-year effect of the package is estimated at 0.49 standard deviations of the IRT scores. Schools in the control group began to receive the package in the second year of research. After 2 years of exposure to the package—as compared with students in the control group who received only 1 year of exposure—the effect is estimated at 0.13 standard deviations. Students in the treatment group advanced their math learning in the second year of research because of the improved understanding in the previous year.