Bridging local craftsmanship and formal geometry in a rural Colombian classroom

This study evaluates a teaching unit based on an ethnomathematical approach, utilizing the cultural knowledge of crafting reed mats to promote metric and geometric thinking. This qualitative study, following an Action Research model, was conducted with 9 fifth-grade students at IED Euclides Lizarazo (Magdalena, Colombia). The intervention adopted an ethnomathematical didactic approach, structured in two interconnected phases: an ethnographic phase, to systematize the mathematical knowledge of three local artisans; and an educational phase, where the teaching unit was implemented using a parallel and comparative teaching method. The results reveal that, starting from a solid cultural knowledge base, students showed heterogeneous progression. A gap was evidenced between the conceptual understanding of measurement and its procedural execution; however, a group of students achieved advanced formal mathematization in geometry. The majority demonstrated sophisticated strategic-numerical thinking. In this regard, the ethnomathematical approach proved effective in connecting local and academic knowledge within a meaningful context.