<![CDATA[This study investigated the improvement of students' mathematics learning outcomes after the implementation of Wordwall-assisted Game-Based Learning (GBL) in a Merdeka Curriculum classroom. The study used a quantitative quasi-experimental method with a one-group pretest-posttest design involving 36 eighth-grade students from a private junior high school in the Sukarame area, Indonesia. The participants were selected purposively because the class showed low initial mathematics achievement and represented the learning context targeted by the intervention. Data were collected using a mathematics learning outcomes test consisting of four essay items aligned with the competency indicators of the Merdeka Curriculum. The instrument was validated prior to the main study and showed acceptable item validity (p < 0.05) and very high internal consistency (Cronbach's alpha = 0.878). Data analysis involved descriptive statistics, the Shapiro-Wilk normality test, a paired-samples t-test, learning mastery analysis, and normalized gain (N-Gain). The results showed that the mean score increased from 34.7 in the pretest to 83.3 in the posttest, with an N-Gain of 0.74, categorized as high. Learning mastery also increased from 0% to 94.4%. The paired-samples t-test indicated a statistically significant difference between pretest and posttest scores (p < 0.001). These findings suggest that Wordwall-assisted GBL was associated with a significant improvement in students' mathematics learning outcomes. However, because this study did not include a control group, the findings should be interpreted as evidence of within-group improvement rather than as definitive comparative causal evidence. Keywords: Game-Based Learning; mathematics learning outcomes; Merdeka Curriculum; pretest-posttest; Wordwall]]>
