This article analyses the influence of time use in various extracurricular activities, such as household chores, paid work, leisure activities and private study, on the gender gap in literacy and mathematics among middle school and high school students in Brazil in 2021, amid the coronavirus disease (COVID-19) pandemic. The Oaxaca-Blinder decomposition is used, enabling results to be broken down to evaluate how structural factors —in particular time use across these activities— affect student performance in Brazil. Our results indicate that unobserved effort in the activity influences performance more than time spent, as returns on activities are more influential than differences in observable gender characteristics for comparable groups. The analysis also concluded that cultural factors remain the primary barrier to reducing the gender gap. The time allocated to extracurricular activities rises in tandem with students’ grade levels, suggesting that prejudice, stereotypes and cultural beliefs increase with age.