The purpose of this study was to create a valid, practical and effective learning tools based on guided discovery to improve the mathematical problem-solving ability of grade VII students of SMP / MTs. The developed learning tools are Learning Implementation Plans (RPP) and Student Worksheets (LKPD). This research is a development research using Plomp model which consists of three stages, namely preliminary research, development stage, and assessment stage. In the development stage, the design

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... nd assessment of learning devices is carried out through the stages of formative evaluation. The subjects of the field test involved in this study were the seventh-grade students of Islamic Junior High School 5 Lima Puluh Kota. The instruments used are lesson plan validation sheet, worksheet validation, teacher response questionnaire, student questionnaire responses. The instruments are firstly validated by mathematicians, linguists, and educational technology experts. The results of the analysis of the lesson plan and worksheet validation sheets show that the developed learning tools are valid. Learning tools are practical based on the results of the analysis of teacher response questionnaires, student questionnaire responses, and learning implementation observation sheets. In addition, the learning tools developed are also effective to improve students' mathematical problem-solving abilities based on the test results. Keywords-learning tools development, mathematics, guided discovery models, and problem solving.