EFEKTIVITAS BUKU SAKU ENGLISH VOCABULARY TERHADAP PENINGKATAN PENGUASAAN KOSAKATA BAHASA INGGRIS SISWA KELAS IV SEKOLAH DASAR

Abstract

English vocabulary mastery is a basic competence that many elementary school students still find difficult, particularly when learning relies on textbooks and verbal explanation. This study aimed to describe fourth-grade students' English vocabulary mastery before and after the use of the English Vocabulary pocket book and to examine the effectiveness of this medium in improving their vocabulary mastery on the topic of animals. A quantitative approach with a pre-experimental one-group pretest-posttest design was used. The population, which was also the sample through total sampling, comprised 30 fourth-grade students of SD IT Al Kautsar Secanggang (17 girls and 13 boys). Data were collected with a validated teacher-rated vocabulary mastery questionnaire administered before and after the treatment, and analysed using descriptive statistics, the Lilliefors normality test, an F test of homogeneity, an independent-samples t-test, and the Mann-Whitney U test as a nonparametric check. The mean score rose from 49.60 to 78.90, a gain of 29.30 points (N-gain = 0.58, moderate). The pre-questionnaire scores did not meet the normality assumption (L = 0.1850 > 0.1610), whereas the post-questionnaire scores did (L = 0.1607 < 0.1610), and the variances were homogeneous (F = 1.1286 < 1.861). The t-test (t = 10.976 > 2.002; p < 0.001; Cohen's d = 2.83) and the Mann-Whitney test (U = 867; p < 0.001) both showed a significant difference, so the null hypothesis was rejected. The English Vocabulary pocket book was moderately effective in improving students' English vocabulary mastery (statistically significant gain, N-gain = 0.58), but the single-group design, the teacher-rated instrument and the small sample call for caution in generalising the findings.