The Didactical Design of Properties of Triangles based on Pecle Traditional Games in Primary School Epon Nur‘aeni 1 , Fitri Rohmayati 2 , Muhammad Rijal Wahid Muharram 3 , Oyon Haki Pranata 4 , Hodidjah 5 , Ika Fitri Apriani 6 {nuraeni@upi.edu 1 , fitrirohmayati@gmail.com 2 , rijalmuharram@upi.edu 3 } Universitas Pendidikan Indonesia Kampus Tasikmalaya, Jl. Dadaha No. 18 Tasikmalaya City 1,2,3 Abstract. The research is based on the emergence of learning obstacles of students on the topic of properties of triangles. The didactical design that the researcher designed is one of the first steps to overcome learning obstacles. The aim of the research was to develop a didactical design of the properties of triangles based on péclé traditional games for third- grade students of primary school. The research was conducted in the City of Tasikmalaya, Indonesia. The study used descriptive qualitative methods. The research instrument is equipped with teaching materials in the form of Student Activity Sheets (SAS). Data collection used is interviews, tests, attitude scale questionnaires and documentation. The results of the study indicate that the design that the researcher can use by teachers and elementary students to enrich the learning design, and can be developed further to minimize the obstacle learning of students in mathematics. Keywords: the properties of triangles, learning obstacles, péclé traditional games 1 Introduction This research is motivated by the results of a preliminary study of the learning obstacles faced by students in learning geometry, specifically regarding the material properties of triangles in grade III elementary school. Learning geometry is important for students to master in order to foster children's logical thinking skills, fostering children's thought processes and learning geometry can provide not just one example [1]. Geometry also is one of the mathematic branches existing from several years old ago [2]. Researchers find learning obstacles faced by students. There are three types of learning obstacles that appear in preliminary studies, as follows: Figure 1 shows some students mistakenly distinguished the names of triangles. Students have difficulty differentiating isosceles triangles and equilateral triangles. In addition, students mistakenly determine the names of the right triangle and random triangles. Figure 2 shows students do not yet know the properties of triangles. In addition, students have not been able to describe the types of triangles precisely. Figure 3 shows students have not been able to give examples of objects that are shaped in the shape of triangles in everyday life. Based on the learning obstacles found, the researcher made a mathematics learning design especially on the properties of triangles based on the Péclé traditional games. Traditional games will play an important role in learning mathematics [3]. In addition, traditional games encourage students to be more creative and work together to become winners [3]. MSCEIS 2019, October 12, Bandung, Indonesia Copyright © 2020 EAI DOI 10.4108/eai.12-10-2019.2296329