Development of Geometry Teaching Materials Assisted Geogebra Android to Improve Mathematical Connection Ability

. This research aims to develop valid, practical, and effective geometry teaching materials with the help of GeoGebra android to improve students' mathematical connection abilities. The method used in this research is research and development. The developing process of teaching materials uses the ADDIE model (Analysis, Design, Development, Implementation, Evaluation). The analysis phase includes an analysis of the needs of learning resources, curriculum, and materials. The design phase includes making a framework of teaching materials, determining reference books, and preparing teaching materials assessment instruments. The development phase includes module development, expert validation, and revision of teaching materials. The implementation phase is the testing phase of teaching materials that are validated and revised to students. The evaluation phase is to analyzes the strengths and weaknesses of the teaching materials that have been tested. The criteria of quality of teaching materials are validity, practicality, and effectiveness. This teaching material is declared valid by assessing the material and media expert with an average of 89% and 85%, respectively. In addition, the module was declared practical by the results of the student response questionnaire, with an average of 78%. Furthermore, based on the results of the student’s mathematical connection ability test, teaching materials are effective in helping students to understand geometrical material and improve their mathematical connection abilities. Based on these results, it can be concluded that the GeoGebra android-assisted teaching materials developed are valid, practical, and effective.