Mahdalena Elma Sari¹, M. Amin Fauzi¹, Faiz Ahyaningsih^1,

This study aims to: 1) Develop teaching materials based on a valid metacognition approach to improve students' understanding of mathematical concepts; 2) Developing teaching materials based on a practical metacognition approach to improve the ability to understand students' mathematical concepts; 3) Develop teaching materials based on an effective metacognition approach; 4) To analyze the increased ability to understand students' mathematical concepts by using teaching materials based on metacognition approaches. This research is a development research using a 4-D development model, the teaching materials developed from this study are: Learning Implementation Plans, Teacher Books, Student Books, Student Worksheets, And Tests Ability To Understand Mathematical Concepts. From the results of trial I and trial II, it was obtained: 1) Teaching materials based on the metacognition approach developed have met valid criteria from several criteria; 2) Teaching materials based on the metacognition approach developed have met Practical criteria from several criteria; 3) Teaching materials based on the metacognition approach developed have met the effective criteria of several criteria; 4) there is an increase in the ability to understand students' mathematical concepts by using instructional materials based on the metacognition approach developed, in the trial I obtained an average score of pretest 54.66% and posttest score 73.86%, and in the second trial with an average pretest score of 57.87% and posttest score of 78.4%.

teaching material development, metacognition approach, 4-D model, ability to understand mathematical concepts