Preschool Quality and Child Development

Global access to preschool has increased dramatically, yet preschool quality is often poor and evidence on how to improve it is scarce. We worked with the government of Colombia to implement a largescale randomized controlled trial evaluating two interventions targeting the quality of public preschools in Colombia. The first, which was designed by the government and rolled out nationwide, provided preschools with significant extra funding, mainly earmarked for hiring teaching assistants (TAs). The second additionally offered professional development training for existing teachers, delivered using a novel low-cost video-conferencing approach. We find that, despite increasing per-child expenditure by around a third, the first intervention did not improve child development and led to a reduction in the time that teachers spent in the classroom, including on learning activities. In contrast, the second intervention led to significant improvements in children’s cognitive development, especially those from more disadvantaged backgrounds, at little extra cost. The addition of the professional development training offset the adverse effects of TA provision on the time teachers spent on learning activities in the classroom and improved the quality of teaching. When we interpret our results through the lens of a model of teacher behavior, two insights arise. First, income effects and a perception that TA time was a good substitute for their own may have led teachers to endogenously scale back their efforts in the classroom in response to the provision of new resources. Second, the training prompted teachers to increase their perception of the usefulness of learning activities for child development and their perception that they had a comparative advantage in these learning activities relative to the TAs