Notes: Each column shows an OLS estimate of a model in which the dependent variable is an outcome measured at baseline (measured by the number of correct answers in that subtask), and the independent variables are dichotomous variables indicating that the students belong to Cohort 2 or Cohort 3. The index shown in Column 4 is a simple average of the scores in the three subtasks shown in Columns 1–3. All models include cohort, year, and strata fixed effects. Standard errors, shown in brackets, are clustered at the school level (the unit of randomization). Significance: ^*p < 0.10, ^**p < 0.05, ^***p < 0.01.