<![CDATA[This study aims to examine the effectiveness of the Wordwall application in improving Arabic vocabulary mastery among students of SMA Muhammadiyah 15 Jakarta. The study is grounded in observed classroom realities in which Arabic vocabulary instruction remained predominantly conventional—teachers writing vocabulary lists on the board for rote memorization—without contextual or repeated reinforcement, leaving most students unable to recall the vocabulary in subsequent lessons. A quantitative quasi-experimental approach with a two-group design was employed: an experimental group (n = 28) using the Wordwall application and a control group (n = 28) receiving conventional instruction, for a total of 56 respondents. Participants were selected through purposive sampling. Data were collected through pretests and posttests, questionnaires, and documentation. Analytical procedures included normality tests (Shapiro-Wilk and Kolmogorov-Smirnov), homogeneity test (Levene), N-gain score calculation, and paired-samples t-test. The results revealed a significant improvement in the experimental group. The pretest mean score was 51.2 with a mastery rate of 0% (no student reached the KKM threshold). Following the Wordwall intervention, the posttest mean rose to 78.5 with a mastery rate of 82.1% (23 of 28 students passed KKM). The N-gain score of 0.7679 (76.79%) classified the intervention effectiveness as “high.” The Levene homogeneity test yielded a statistic of 1.577 (p = 0.214 > 0.05), indicating that the groups have equal variances. The paired-samples t-test yielded a p-value of 0.000 (p < 0.05), indicating a statistically significant difference between pretest and posttest scores in the experimental group. In conclusion, the Wordwall application is empirically validated as significantly more effective than conventional instruction for Arabic vocabulary acquisition. This study fills a gap in the literature by providing evidence from an Islamic-based public high school in Jakarta, using a two-group design and standardized effect measurement via N-gain scores—dimensions that are underrepresented in prior Arabic vocabulary research at the senior secondary level. Keywords: Arabic Language Teaching, Arabic Vocabulary Mastery, Wordwall Application]]>
