expected to deliver. The package also included activities booklets for the students, which were the same as in the first treatment arm but without the self-paced content elements.

For all treatment arms and the control condition, the responsible teacher was the headteacher, who was assigned by the school at the start of the school year to each class.

_Table 1: Summary of Intervention_

|||**Experimental Condition**<br>||
|---|---|---|---|
||**Treatment 1**|**Treatment 2**|**Control**|
|**Target**|Students|Students and teachers|No intervention|
|**Delivery**|Student self-learning|Teacher-delivered lessons||
|**Timing**|1 lesson per week: First<br>class hour on Monday|1 lesson per week: First class<br>hour on Monday||
|**Role of Teachers**|No teacher involvement|1 dayteacher training||
|**Lessons**|5 lessons: (1) “Introduction”<br>cus 100%”(4)“Seek Feedba|(2) “Choose Challenge” (3) “Fo-<br>ck”(5)“Reflect,Refine,Repeat”||
|**Data Collection**|3 sessions(basel|ine,endline,and additional data col|lection)|

# **3. Data**

We collected data on two categories of outcomes:

- (1) Socio-emotional skills, which include _(i)_ deliberate practice beliefs (as a manipulation check variable), _(ii_ ) the Short Grit Scale (Duckworth and Quinn, 2009), _(iii)_ a measure of frustration reaction, _(iv)_ the Motivational Frameworks Questionnaire (Gunderson et al., 2013), _(v)_ and locus of control (Skinner et al., 1990), and _(iv)_ present bias. All outcomes were measured using tested and validated self-report scales, which were adapted to children from North Macedonia and translated (back-and-forth) to Macedonian and Albanian languages.<sup>14</sup>

- (2) GPAs at different points in time as a measure of academic achievement: short-term, i.e. immediately after the intervention in the fourth quarter of the school year 2015/2016; medium-term, i.e. half a year later in the second quarter of the school year 2016/2017; and longer-term, i.e. one year later in the fourth quarter of the school year 2016/2017. In North Macedonia, grades are recorded on a one-to-five scale, whereby one denotes the lowest and five the highest grade.

Data on the different socio-emotional skills and students’ socio-economic characteristics (which are otherwise not available in official records) were collected through baseline and endline surveys. To analyze whether the intervention shifted socio-emotional skills generally, and to reduce issues around dimensionality and multiple hypotheses testing, we construct a socio-emotional skills index (S/E skills index) that summarizes the different measures of self-reported socio-emotional skills. It combines the measures of deliberate practice beliefs, grit, frustration reaction, motivational frameworks, locus of control, and present bias. Following Anderson (2008), we construct this index by _(i)_ switching the sign of the variables included in the index (if needed), so that a positive direction always indicates a "better" outcome; _(ii)_ standardizing each variable (to have mean zero and standard deviation one, i.e. z-scores); _(iii)_ averaging the standardized variables using appropriate weights (i.e. the inverse of the variance-covariance matrix of the standardized variables) to ensure that highly correlated items receive less weight while variables that are uncorrelated and hence represent new information receive more; and then _(iv)_ standardizing the resulting index.

Data on GPAs come from official, administrative records held by the Ministry of Education in North Macedonia. We exploit all grades given to the students during the school years 2015-2016 and 2016/2017, the

> 14 Survey questions used to collect baseline and endline data are available upon request.

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