This research describes the concepts of ethnomathematics in the Sambas Malay Gasing game activity and its application in mathematics learning in the form of Student Worksheets. This study was motivated by the researcher"™s concern about today"™s students who have forgetten the culture. Then the difficulty of students understanding learning at school is due to the lack of application of local culcure-based mathematics learning. Mathematics and culture are inseparable. With this ethnomathematics study of the gasing game, it is hoped that it can bridge mathematics learning in schools with students"™ socio-cultural lives. This research is an exploratory descriptive research. Data collection techniques with observation, interviews and documentation, then analyzed with data reduction and drawing conclusions. The result showed that: 1) There are mathematical concepts in the activities of making and playing gasings, namely the concepts of curved side lines, beams, prisms, tangent lines, intersecting lines, congruence, cartesian coordinates, circles, perpendicular lines, rectangular flat shapes (square, rectangle, and trapezoid), parallel lines, phytagoras theorem, probability, logic and sets, even numbers,standard units (weight and length), mathematical activities of grouping, counting, measuring, designing, determining location, and explaining; and 2) The application of this research is in the form of worksheets for grade IX Junior High School students on the geometry of curved side spaces based on mathematical concepts in the Sambas Malay gasing game.
