THE EFFECTIVENESS OF MYSTERY BOX AS A LEARNING MEDIA ON VOCABULARY MASTERY OF GRADE FIVE STUDENTS AT SDN 1 BUKIT SAWIT

Vocabulary mastery is an important component of English language learning, particularly for young learners. Therefore, interactive learning media are needed to provide meaningful and engaging vocabulary learning experiences. One of the media that can be used is Mystery Box, which incorporates vocabulary cards and real objects into classroom activities. This research aimed to investigate the effectiveness of using Mystery Box as a learning media on the vocabulary mastery of Grade Five students at SD Negeri 1 Bukit Sawit.
This study employed a quantitative approach with a pre-experimental one-group pre-test-treatment-post-test design. The participants were 22 Grade Five students who participated in the pre-test, two treatment sessions, and the post-test. The data were collected through a 20-item vocabulary test consisting of 10 matching items and 10 multiple-choice questions. The instrument was validated through expert judgment and tested for reliability using Cronbach’s Alpha, which produced a coefficient of 0.862. The data were analyzed using descriptive statistics, the Shapiro-Wilk normality test, and the Wilcoxon Signed-Rank Test.
The results showed that the students’ mean score increased from 72.73 in the pre-test to 91.36 in the post-test, with an improvement of 18.63 points. The Wilcoxon Signed-Rank Test produced a Z value of −4.128 and an Asymp. Sig. (2-tailed) value of 0.000 (< 0.05). All 22 students obtained positive ranks, indicating that their post-test scores were higher than their pre-test scores. Therefore, H₀ was rejected and Hₐ was accepted, indicating a statistically significant improvement in students’ vocabulary mastery after the implementation of Mystery Box. The findings showed that Mystery Box can be used as an interactive, simple, and easy-to-apply learning media and instructional aid for vocabulary learning. Therefore, English teachers are recommended to consider Mystery Box as an alternative medium for teaching daily-items vocabulary.