Abstrak
This study aimed to determine whether there was a significant difference in English speaking skill between the eleventh-grade students at SMAN 1 Nunukan, which applied the Merdeka Curriculum, and SMAN 2 Nunukan which implemented the 2013 curriculum. A causal-Comparative research design was employed, with a sample of 114 students selected through purposive sampling. The research instrument consisted of an 11-item speaking test adopted from TOEIC Collins Speaking Test. The data, thouh not normally distributed, were found to be homogeneous, and as a result, the Mann-Whitney U Test was used for analysis. The two schools, as indicated by a p-value pf 0.000. Students from SMAN 1 Nunukan following the Merdeka Curriculum, achieved a mean score of 125.32 corresponding on TOEIC level 6 and CEFR level B1 (Intermediate). In contrast, students from SMAN 2 Nunukan, using the 2013 Curriculum, averaged 92.12, placing them at TOEIC level 4 and CEFR level A2 (Elementary). The effect size was calculated at 0.361, indicating a medium-level difference between the groups. This difference in speaking skill might be attributed to the differences in the two curricula, with Merdeka Curriculum offering greater flexibility in teaching and learning approaches, whereas the 2013 Curriculum tended to be more structured and systematic.