<![CDATA[The collaboration skills and conceptual understanding of 11th-grade students at MAN 2 Yogyakarta are still relatively low, even though these are 21st-century skills that every student should possess. This study aims to determine the effect of the Student Teams Achievement Division (STAD) cooperative learning model combined with the Make a Match method on students' collaboration skills and conceptual understanding of the human body defense system material in grade XI at MAN 2 Yogyakarta. This study used a quantitative, quasi-experimental approach with a nonequivalent control group design and was conducted during the even semester of the 2025/2026 academic year. Using purposive sampling, 70 grade XI students were selected, comprising class XI C as the experimental group and class XI E as the control group, each with 35 students. Data were collected through observation, questionnaires, and tests, then analyzed descriptively and inferentially using the Shapiro-Wilk normality test, Levene's homogeneity test, the Mann-Whitney test, and the effect size test. Results showed that the STAD model with the Make a Match method had no significant effect on students' collaboration skills (Sig. 0.05) but had a significant effect on conceptual understanding (Sig. 0.05), with a small effect size of 8.10%. The model is thus effective in improving conceptual understanding, though not yet effective in improving collaboration skills. This research can serve as a reference for teachers implementing innovative learning in the classroom.]]>
