Indonesian Research Journal on Education Web Jurnal: https://irje.org/index.php/irje Indonesian Research Journal on Education Volume 4 Nomor 4 Tahun 2024 e-ISSN: 2775 – 8672 p-ISSN: 2775 – 9482 1587 Improving Vocabulary Mastery by Explicit Instruction for Elementary Students Demisari Harmades Prodi Pendidikan Bahasa Inggris, UIN Mahmud Yunus Batusangkar, Indonesia demisari02@gmail.com Abstrak Kata Kunci: Kosakata, Pengajaran Eksplisit, Siswa Sekolah Dasar. Penguasaan kosakata merupakan elemen penting dalam keterampilan berbahasa yang memengaruhi pemahaman literasi dan kemampuan komunikasi siswa sekolah dasar. Namun, metode pengajaran kosakata yang sering diterapkan di sekolah masih cenderung menggunakan pendekatan konvensional, yang kurang efektif dalam meningkatkan pemahaman mendalam dan retensi jangka panjang siswa. Penelitian ini bertujuan untuk mengevaluasi efektivitas pengajaran eksplisit dalam meningkatkan penguasaan kosakata pada siswa sekolah dasar. Metode penelitian yang digunakan adalah kuasi-eksperimen dengan desain pretest-posttest control group, melibatkan 60 siswa yang terbagi dalam kelompok eksperimen (pengajaran eksplisit) dan kelompok kontrol (pengajaran konvensional). Hasil penelitian menunjukkan bahwa kelompok eksperimen mengalami peningkatan skor kosakata yang signifikan setelah diberikan pengajaran eksplisit, dengan perbedaan rata-rata skor sebesar 24,4 poin dibandingkan kelompok kontrol yang hanya meningkat 7,1 poin. Uji statistik menunjukkan perbedaan signifikan antara kedua kelompok (p-Value < 0,05), mengindikasikan efektivitas pengajaran eksplisit dalam meningkatkan penguasaan kosakata siswa. Selain itu, retensi kosakata juga lebih tinggi pada kelompok eksperimen dua minggu setelah posttest, menunjukkan bahwa pengajaran eksplisit berperan dalam mempertahankan kosakata jangka panjang. Observasi selama proses pembelajaran juga menunjukkan peningkatan partisipasi siswa pada kelompok eksperimen, yang menandakan pengaruh positif terhadap motivasi dan keterlibatan siswa. Pengajaran eksplisit terbukti efektif dalam meningkatkan penguasaan kosakata dan keterlibatan siswa dalam pembelajaran bahasa di sekolah dasar. Penelitian ini merekomendasikan pengajaran eksplisit sebagai metode yang efektif dan dapat diimplementasikan secara luas dalam kurikulum pendidikan dasar. Abstract Key Word: Vocabulary, Explicid Instruction, Elementary Students. Vocabulary mastery is a crucial element in language skills that influences literacy comprehension and communication abilities among elementary students. However, vocabulary teaching methods frequently used in schools still tend to rely on conventional approaches, which are less effective in fostering deep understanding and long-term retention. This study aims to evaluate the effectiveness of explicit teaching in enhancing vocabulary mastery among elementary school students. The research employed a quasi- experimental method with a pretest-posttest control group design, involving 60 students divided into an experimental group (explicit teaching) and a control group (conventional teaching). The study's results indicated that the experimental group experienced a significant increase in vocabulary scores following explicit instruction, with an average score difference of 24.4 points compared to the control group, which showed only a 7.1-point improvement. Statistical tests revealed a significant difference between the two groups (p-Value < 0.05), suggesting the effectiveness of explicit teaching in enhancing students' vocabulary acquisition. Additionally, vocabulary retention was higher in the experimental group two weeks after the posttest, indicating that explicit instruction aids in long-term vocabulary retention. Observations during the learning process also showed increased student participation in the experimental group, reflecting a positive impact on student motivation and engagement. Explicit teaching proved effective in improving vocabulary mastery and student engagement in language learning at the elementary level. This study recommends explicit teaching as an effective method that can be broadly implemented within the elementary education curriculum. Copyright © 2024 Demisari Harmades This work is licensed under an Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) INTRODUCTION Vocabulary mastery is an essential foundation in language proficiency, influencing students’ reading comprehension, speaking skills, and writing abilities (Nation, 2001). For elementary students, adequate vocabulary mastery is crucial, as it forms the basis for further language skill development. In the elementary school context, vocabulary serves as a bridge between literal understanding and deeper comprehension of texts, ultimately playing a critical role in their academic success (Beck, McKeown, & Kucan, 2013). However, Indonesian Research Journal on Education e-ISSN: 2775 – 8672, p-ISSN: 2775 – 9482 Volume 4 Nomor 4 Tahun 2024 Halaman: 1587 – 1593 RESEARCH ARTICLE Web: https://irje.org/index.php/irje