year in which the intervention took place and the year after. As the intervention targeted both sixth and seventh-grade students, we focus on the set of core subjects that are common to both years: math, English, and the student’s first language (which can be either Macedonian or Albanian). Arguably, these are also the subjects that are most decisive for later educational transitions, for example the transition from primary to secondary school, which occurs in North Macedonia after grade nine.

After calculating GPAs from math, English, and language, we classify them into either pre-treatment or post-treatment depending on the date when they were recorded. As the intervention was implemented in the third quarter of the school year 2015/2016 (to be precise, between February 15 and March 21, 2016), the post-treatment GPA is calculated over the period of the fourth quarter (March 21 to August 31, 2016). Besides these short-run GPAs, we also calculate medium-run (first and second quarter of the school year 2016/2017) and long-run GPAs (third and fourth quarter of the school year 2016/2017). The pre-treatment GPA is calculated over the entire academic year 2015/2016, right up to the start of the intervention. When calculating GPAs, we are agnostic and treat both written and oral grades – both of which are recorded – as equally relevant.<sup>15</sup> Furthermore, students, depending on the subject and school year (i.e. sixth or seventh grade), may differ in the number of exams or tests they take, and accordingly, in the number of grades they receive, as well as in the share of these that comes from written or oral exams.<sup>16</sup> Unfortunately, standardized tests were not available in the country at the time of the intervention. As with our socio-emotional skills measures, we standardize GPAs to have mean zero and standard deviation one (i.e. z-scores).

It should be noted that our administrative data do not include the precise dates when exams or tests were taken, but only the (precise) dates when the resulting grades were recorded by teachers. Our approach to construct GPAs is, therefore, agnostic, in that we exploit sharp cut-offs based on official school year and quarter beginning and end dates to determine whether a specific grade is pre or post treatment. This is a conservative approach, as pre-treatment grades based on exams or tests taken just before the start of the treatment quarter may only be recorded in the treatment quarter, and may thus be intermingled with posttreatment grades, deflating these and resulting in lower-bound estimates.<sup>17</sup> While this type of bias works in favor of positive results, we believe that it is quantitatively rather minor, for several reasons: first, teachers are strongly encouraged to record grades as soon as possible, ideally within two weeks after the respective exam or test was taken. Second, the vast majority of assessments are taken at the end of the second and fourth quarter of the school year (i.e. after the first and second semester, before winter and summer holidays), and only a small fraction in-between. Our intervention, however, was implemented in the third quarter while our post-treatment GPAs are constructed from fourth-quarter grades only. That said, there was only a small fraction of assessments occurring just before the fourth quarter which could have spilled over. Finally, note that, even if spillover would occur, it is unlikely to cause systematic bias, as such spillover is likely to be balanced across groups due to randomization, unless teacher grade-reporting behavior has changed systematically between groups. However, we find little evidence for this.

We test the latter formally by comparing the number of grades recorded in the fourth quarter between groups. Teachers in the control group reported about 35% of all grades (σ=0.48), those in the first treatment group (“student self-learning”) 31% (σ=0.46) and those in the second treatment group (“teacher delivery”) 28% (σ=0.45). Calculating normalized differences between the treatment groups and the control group to

> 15 The type of test has equal weight for students’ GPA at the end of the school year. We conducted sensitivity analyses with respect to oral and written grades separately but these did not result in qualitatively different findings. The results are available on request.

> 16 Such differences are unlikely to bias our results as these are balanced between experimental groups.

> 17 We experimented with constructing GPAs using various lags (e.g., using a delay of two weeks at the beginning of the fourth quarter rather than using its sharp start date). However, our findings remained qualitatively very similar to our baseline results using the sharp cut-off dates of the school year calendar.

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