This study introduces and evaluates the GIBAC Learning Model, aimed at enhancing students’ mathematical communication skills in Indonesian secondary schools, achieving an impressive 30% increase in students’ mathematical communication skills as evidenced by the n-gain method and dependent t-test analysis. Grounded in cooperative learning theory and motivation, the model integrates local academic culture and promotes student independence, offering a promising avenue for educational advancement in Indonesia. Employing a Mixed Methods approach, data from three secondary schools were collected via cluster random (...) sampling, encompassing interviews, observations, expert assessments, and questionnaires. Analysis reveals the model’s effectiveness in improving mathematical communication skills, underscoring its relevance to Indonesian educational practices. Practical implications for teachers emphasize the integration of cultural aspects and student autonomy in mathematics education, thereby contributing to the advancement of educational literature through Indonesian innovation and cultural adaptation in pedagogical frameworks. (shrink)