_Table 4a: Impacts on S/E Skills Index and Different Sets of Skills (Z-Scores)_

||Including All Skills<br>(1)|S/E Skills Index<br>Excluding Deliberate<br>Practice Beliefs and Grit<br>(2)|Only Including Deliberate<br>Practice Beliefs and Grit<br>(3)|
|---|---|---|---|
|Treatment 1|0.055**|-0.004|0.070***|
|“Student Self-Learning”|_(0.022)_|_(0.022)_|_(0.020)_|
|Treatment 2|0.128***|0.063***|0.133***|
|“Teacher Delivery”|_(0.021)_|_(0.021)_|_(0.021)_|
|N|18,718|18,718|18,718|
|N Control|7,286|7,286|7,286|
|N Treatment 1|5,424|5,424|5,424|
|N Treatment 2|6,008|6,008|6,008|
|_R2_|_0.337_|_0.345_|_0.308_|

* p < 0.05, ** p < 0.01, *** p < 0.001

_Notes:_ All regressions control for pre-treatment outcomes, demographic controls (including dummies for age, gender, academic year, and ethnicity), and municipality fixed effects. Robust standard errors are clustered at the school level. All figures are rounded to three decimal places.

_Source:_ Own survey data, school year 2015/2016, own calculations.

Table 4a shows that our intervention had a significant, positive impact on our S/E skills index on average (Column 1), with stronger impacts in the teacher-delivery treatment (about 13% SD) compared to student self-learning (about 6% SD). Disaggregating the index into the different sets of skills that are included, in particular deliberate practice beliefs and grit _versus_ all others, we find that, while all other skills do play a role in the teacher-delivery treatment (Column 2), deliberate practice beliefs and grit are clearly the driving forces, being twice as important in terms of effect size as all other skills (which turn out to be entirely insignificant when it comes to student self-learning (compare Columns 2 and 3).

Next, we turn to our main analysis in Table 4b. Panel A shows the impact of our intervention on our S/E skills index, on average (Column 1) and for different sub-groups defined by gender (Columns 2 and 3), ethnicity (Columns 4 to 7), grade (Columns 8 and 9), and tercile in the pre-treatment S/E skills distribution, whereby the first tercile is the lower and the third tercile the upper end (Columns 10 to 12).

When it comes to heterogeneous treatment effects by gender, the impact of both treatments is positive for girls and for boys, but they are larger for girls. Moreover, treatment effects are slightly larger for students of Macedonian ethnicity (the largest ethnic group in the country) than for students of Albanian ethnicity (the second largest group). They turn out especially large for Roma students (the most disadvantaged group), for whom the impact of the teacher-delivered treatment is about 42% SD (Column 6). The finding for Roma students should be taken with caution, though: in this heterogeneity analysis, sample size drops substantially. Columns 8 and 9 show similar impacts of the intervention on sixth and seventh grade students, whereas Columns 10 and 12 show that impacts are larger for students who already a had higher level of S/E skills to begin with (those in the second and third terciles of the pre-treatment S/E skills distribution). We cannot reject that there are no statistically significant differences between groups reported in Columns 2 to 12.

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