Ethnomathematics of harmonic movement: line and series patterns in the Ratoh Jaroe dance

This study aims to represent wave motion as a form of application of mathematical concepts in the Ratoh Jaroe dance culture. This dance is known for its compactness and regularity of dancer movements, showing the up-down pattern of hands and formation of rows that resemble sinusoidal waves. This movement can be modeled as a periodic sequence, where the position of the dancer's hands (up, middle, down) can be interpreted as a repeating number value forming a mathematical pattern. The subjects in this study were former members of the Mirah Delima Studio from Almuslim University, Aceh. Through an ethnomathematics approach and ethnographic method, this study examines this traditional Acehnese dance not only as an artistic expression, but also as an alternative learning medium that is contextual and meaningful. The results of the study indicate that the wave pattern in the Ratoh Jaroe Dance can be used to introduce the concept of sequences, series, and wave functions to students, so that mathematics learning becomes more interesting, effective, and rooted in local wisdom.