Recent global challenges like the COVID-19 pandemic have highlighted the growing importance of children learning 21st-century skills for adaptation and flexibility. Competence-based curricula encourage creativity and problem solving but little is known about their development in low-income countries or relationship with conventional academic outcomes like literacy. This study examines pupils’ cognitive flexibility, the underlying basis for many 21st-century skills, in Rwandan primary schools and finds little association with their reading abilities. The findings advance international knowledge regarding child development in resource-poor contexts, suggest a need for more holistic measurement and offer a new approach for understanding learners’ adaptability.