Student Mindsets Matter: Experimental Evidence from a Growth Mindset Intervention in Brazil

This study examines the impact of an SMS-based growth mindset training on secondary students in São Paulo State, Brazil, in the aftermath of the pandemic. We implemented a cluster-randomized design involving 108,345 students across 624 schools. We assigned students to one of five treatment groups, each emphasizing different potential mechanisms associated with the growth mindset literature, or a control group. Pooling the different SMS content variations, the intervention led to a 10% increase in the prevalence of growth mindset among treated students compared to the control group. The treatment also decreased student absenteeism by half as in-person classes resumed. These effects are twice as large as those observed in a placebo treatment group, whereby students received messages without growth mindset content. Different from previous findings in the literature, we estimate significant and sizeable average treatment effects on standardized test scores: the intervention increased the control average learning rate over that period by up to 68%. Among the five different content variations, messages emphasizing dynamic complementarities of school effort outperformed other treatments, such as those emphasizing returns to effort or risk-taking, in promoting growth mindsets and enhancing learning outcomes.