Abstract This research aimed to develop a booklet based on Tugas Pengajuan Soal Open Ended (TPSOE) Mathematics Vocabulary from the Intangible Cultural of Dayak Bidayuhsomu Desa Sebuduh Kecamatan Kembayan as learning source in the material of algebra at 7th grade of Junior High School. The use of TPSOE booklet is an application of ethnomathematics at school. This was qualitative research with descriptive method. The subject in this research were mathematic teachers of 7th grade of Junior High School, while the object was material of algebra based on Kompetensi Dasar 3.6 from Kurikulum 2013 syllabus. The instrument used is validation questionnaire which refers to BSNP consist of content validity, presentation, language, and graphic components. The TPSOE booklet validated by three lectures and a teacher. The result revealed that the TPSOE booklet was valid to be used as a learning source. All of the components got a score which categorized as very good, content validity component got 95,19%,, presentation component got 96,25%, language component got 97,50%, and graphic component got 97,79%. Keyword: Algebra, Booklet, Ethnomathematics, Mathematics Vocabulary, TPSOE.
