This research aims to develop LKPD based on Problem Based Instruction (PBI) for students' mathematical problem solving abilities. This type of research is the research and development (R&D) ADDIE development model. Validity, practicality and effectiveness are the three kinds of instruments to be analyzed. The research subjects for the validity test are lecturers as media experts and teachers as material experts. While the practical and effectiveness test subjects were thirty eighth graders. The research instruments used are questionnaires and tests. The data analysis techniques used are qualitative data analysis from validator comments and suggestions and quantitative data analysis in the form of scoring the percentage of validity, practicality and effectiveness of LKPD. Research conclusions: (1) Problem Based Instruction (PBI)-based LKPD on opportunity material meets the criteria, is very valid, very practical and very effective and can be used in the student learning process (2) Student learning outcomes after participating in learning using Problem Based Instruction (PBI)-based LKPD have met the expected problem-solving ability indicators.