EFEKTIVITAS PEMBELAJARAN BERBASIS METODE MONTESSORI TERHADAP KESIAPAN KOGNITIF DAN SOSIAL EMOSIONAL SISWA KELAS I SEKOLAH DASARNIM.: 23204082029NurjannahauthorThis study aims to analyze the effectiveness of Montessori-based instruction on the cognitive and socio-emotional readiness of first-grade elementary school students during the transition from kindergarten to primary school. A mixedmethods approach with a sequential explanatory design was employed, combining quantitative and qualitative data to obtain a comprehensive overview. The study involved two groups: an experimental group receiving Montessori instruction and a control group receiving expository (conventional) instruction. Data were collected through cognitive readiness tests, socio-emotional readiness questionnaires, interviews, observations, and documentation. The results indicate a significant difference between students taught using the Montessori method and those taught using the expository method regarding both cognitive and socio-emotional readiness. Montessori instruction proved more effective in enhancing students' cognitive abilities, particularly in the areas of sensory perception, mathematics, and language. Cognitively, the Montessori group achieved an average score of 90.43, compared to 78.05 for the control group. Furthermore, the method supported students' socio-emotional development by fostering independence, positive social interaction, and improved emotional regulation. The difference was even more pronounced in the socio-emotional domain—with scores of 81.86 versus 68.24 where 86% of Montessori students reached the high category, far exceeding the 19% observed in the control group. Both results were statistically significant (p = 0.000). From the teachers' perspective, the implementation of Montessori helped create a learning environment that was more structured, meaningful, and aligned with children's developmental needs. Students perceived the Montessori approach as more enjoyable, noting that it made them more active, confident, and capable of independent learning. Thus, the Montessori method is considered highly effective in supporting the cognitive and socio-emotional readiness of first-grade students during the initial transition to primary school. These findings confirm that the Montessori approach offers a child-friendly and relevant educational alternative for bridging the transition from early childhood education to primary school.371.36 Metode Pengajaran, Metode Pembelajaran2026-07-09UIN SUNAN KALIJAGA YOGYAKARTA;FAKULTAS ILMU TARBIYAH DAN KEGURUANThesis