the United States<sup>6</sup> (see also Paunesku et al, 2015);<sup>7</sup> Bettinger et al. (2018) adapted the tools from the Yeager et al. study in a small sample in rural Norway, replicating their results.<sup>8</sup> Also, Alan et al. (2019) randomly assigned fourth-grade students to 12 two-hours sessions in Istanbul, Turkey, and show this led to persistent improvements in math test scores by 20% of a standard deviation.<sup>9</sup> While encouraging, recent experimental evidence equally shows that these interventions can also be ineffective (Foliano et al., 2019; Ganimian, 2019). Furthermore, a recent meta-analysis that analyzes results from 29 studies shows mixed evidence of impacts on academic achievement (Sisk et al., 2018). To our knowledge, no study has demonstrated whether a growth mindset intervention can be successful in the context of low-and-middle-income countries.<sup>10</sup> With millions of students around the globe attending schools of insufficient quality 6 Yeager et al. (2019) randomly assigned a 50-minute (2 sessions, 25 minutes each), online intervention in a sample of low-achiever students from the ninth-grade. Students come from a national sample of 65 regular public secondary schools in the United States.

7 Mueller and Dweck (1998) show that students whose effort is praised improved their performance in math test scores by 30% compared to students whose intelligence is praised. Blackwell et al. (2007) administered 8-sessions of 25 minutes each (one per week) in which the science of the brain was explained to students, in particular how brain connections grow, and people become more intelligent when faced with challenges. As part of these sessions, students were asked to read a brief text that described the science behind the growth mindset (“You can grow your brain”). Subsequently, students were asked to think about examples in which their performance had improved through practice. Finally, they were asked to write a letter to younger students explaining the concepts learned –this was to help persuade them about the concepts learned through cognitive dissonance (Aronson, 1999). By the end of the academic year, an improvement in math test scores by 0.2 standard deviation was detected. Good et al. (2003) used a mentorship strategy (which included sessions for two months, and email exchanges with the mentor during the school year). They found positive effects on math test scores among women by around 0.2 standard deviation. Aronson et al. (2002) developed a similar intervention in which they worked with mentors that were in the last years of college to teach the growth mindset to first-year college students –and found an impact on final scores of 0.29 standard deviation. Paunesku et al. (2015) randomly assigned a 45-minute online session to students (the sample, 1,594 students in 13 schools, was larger than previous studies). During the session, students were asked to read an article about the growth mindset, and then to write letters to other students about the ideas learned. By the end of the semester, students from the intervention group were 6.4 p.p. more likely to have a satisfactory score in their main course.

8 Bettinger el al. (2018) randomly assigned a 135-minute, online intervention (3 sessions, 45 minutes each) among 345 students in 1 rural school in Norway.

9 Alan et al. (2019) randomly assigned the intervention at the school level in a sample of 16 schools in Turkey (Istanbul).

10 Ganimian (2019) randomly assigned a short-lived intervention at the school level in a sample of 202 urban, public secondary schools in Argentina (province of Salta), with a focus on 3