To be able to estimate whether the project produced the desired effects of raising overall pre-numeracy skills and closing learning gaps, we needed to estimate what would have happened in the absence of the Tikichuela project. To do this, we conducted an experiment in which preschools were randomly assigned to either a treatment or a control group. These types of randomized control trials (RCTs) have been used to evaluate the effects of various education inputs, such as textbooks and computers (Barrera-Osorio & Linden, 2009; Malamud & Pop-Eleches, 2011; Cristia, Cueto, Ibarraran, Severin, & Santiago, 2012), scholarships (Glewwe, Hanushek, Humpage, & Ravina, 2011), and tutoring (Banerjee, Cole, Duflo, & Linden, 2007).
The randomized design covered 265 school districts in the department of Cordillera, or approximately 4,500 preschool students and 400 teachers. One hundred and thirty-one schools were randomly selected to receive the treatment, while the remaining 134 schools were designated as the control group. The sample was stratified based on school location (urban-rural), school resources (high-low resources), number of children enrolled, and existence of split sessions schedule (one-two sessions).