In Table 1, we summarize the characteristics of schools (Panel A), teachers (Panel B) and children (Panel C) in our sample. Panel A shows that the average school in the sample had 4.7 teachers between kindergarten and 3<sup>rd</sup> grade. These values, as well as the proportion of teachers in different pay grades in the salary scale, are similar in treatment and control schools. Panel B shows that essentially all (98 percent) of teachers are women, and most (90 percent) are tenured. On average, teachers have almost 16 years of experience and 31 children in their classrooms. Panel C shows that half of the children in the sample are girls, and average age (measured at the end of the grade, when children took the achievement tests) is 7 years. There are small differences in child age and gender by treatment status: Children in the treatment group are about 0.7 months older than those in the control group and are 4 percentage points more likely to be female. In our estimates, we control for all school, teacher, and child characteristics in Table 1.

We provide further details on the CLASS in the Appendix. Figure A1 graphs univariate densities of the distribution of CLASS scores for teachers in the control group, by domain. The figure shows that CLASS scores are highest in _Classroom Organization_ , with teachers distributed in the “medium” and “high” parts of the distribution; somewhat lower in _Emotional Support_ , with most teachers in the “medium” range; and lowest in _Instructional Support_ , where all teachers have “low” CLASS scores. There are clearly floor effects for _Instructional Support_ , but not the other domains. On average, the CLASS scores in this sample are somewhat higher than those found in a nationally representative sample of kindergarten classrooms in Ecuador, but substantially lower than those generally found in U.S. settings (Araujo et al. 2016). Table A1 shows that CLASS scores across domains for the same teachers are positively correlated, with correlations that range from 0.43 for _Emotional Support_ and _Instructional Support_ to 0.69 for _Emotional Support_ and _Classroom Organization_ . The fact that the correlation between teacher scores on the different domains of the CLASS are far from unity likely reflects a combination of factors: Different teachers may genuinely excel in the behaviors in different domains, but measurement error would also tend to reduce the magnitude of the correlations.

Within each classroom, we used a random number generator to select a sample of 20 children who would be tested at the end of the year.<sup>6</sup> To measure achievement, we applied two language and two math tests. The language tests were a test of letter and word recognition and a test of receptive vocabulary, while the math tests were a test of number recognition and a test of simple addition and subtraction. To measure receptive vocabulary, we use the _Test de Vocabulario en Imagenes Peabody_ (TVIP)

> 6 With 198 classrooms and 20 children per classroom, our target number of children with test score data was 3,960. However, there were 9 classrooms that had fewer than 20 children in total. Accounting for these classrooms results in 3,909 children. Our final sample, 3,751 children with valid test score data, is 96 percent of the intended sample.

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