This research is aimed to determine the role of Indonesian folklore context namely the Legend of Kemaro Island in supporting average learning on 6 grade students with Pendidikan Matematika Realistik Indonesia (PMRI) approach. The method used is a design research that contains three stage namely preliminary design, teaching experiment, and retrospective analysis. Results from the research shows that Indonesian folklore context can support students to develop their knowledge in the concept of average. Strategy and model (emergent modeling) that students discover, describe and discuss the construction or contribution shows how students can use to help their initial understanding of the concept of average.