We invited 55 public secondary schools in the Santiago metropolitan area to participate in the study. A representative from the non-profit met with the principal of each of these schools to invite them to participate the evaluation.
52 schools accepted to participate. They were located across different districts (municipios) within Santiago, including: El Bosque, La Granja, Pedro Aguirre Cerda, San Bernardo, Santiago y Santo Domigo.
We randomly selected two grade 1 and two grade 3 sections per school. Then, a representative from the non-profit met with all the principals of sampled schools to explain the requirements of the program and the evaluation and collect their baseline data. This process resulted in 3,300 students who were entered into a lottery roster.