Development of Discovery Learning Tools to Facilitate Junior High School Students’ Mathematical Understanding Ability

This research and development (R&D) aim to produce learning tools in the form of syllabus, lesson plans (RPP), student worksheets (LKPD) based on discovery models geometry flat-side materials facilitate mathematical understanding ability 8th-grade students junior high school that has met valid practical requirements. The model used is 4-D, consisting four stages: Define, Design, Development, Disseminate. instruments this are validity validation sheets practicality response questionnaires. RPP, LKPD been developed validated by three validators then tested out. According data analysis results, have requirements with an average score syllabus 3.93, RPP 3.86, 3.80. questionnaire showed small group trials 3.61 large 3.53. Thus, be school.