Repository Universitas Nusantara PGRI KediriEXPLORING STUDENTS’ SELF-DIRECTED ENGLISH VOCABULARY LEARNING THROUGH DUOLINGO: A CASE STUDY OF JUNIOR HIGH SCHOOL STUDENTSNaufalFahmiauthorThe purpose of this research was to explore and understand the dynamics of self-directed English vocabulary learning through Duolingo outside the formal classroom setting, focusing specifically on the learning motivation and consistency of adolescent EFL learners. Independent language practices in informal settings are highly critical for transitioning passive vocabulary into active production. However, secondary school students frequently face challenges in maintaining self regulation, combating technical friction, and overcoming external distractions without direct teacher supervision. To address this phenomenon, the present study was conducted in the academic year 2025/2026 employing a qualitative case study design. The participants of this study consisted of junior high school students aged 12 to 15 years old who actively utilized Duolingo as a complementary digital learning platform. Data were collected through in-depth semi-structured interviews, observations, and student documentation, and were subsequently analyzed using the interactive analysis model by Miles, Huberman, and Saldaña. The research findings revealed that the process of self-directed vocabulary learning through Duolingo demonstrates a structured yet flexible language acquisition routine. Students strategically integrated application usage into their daily downtime, reflecting high levels of automaticity. Furthermore, students’ autonomous interaction was heavily driven by a dynamic interplay of internal psychological needs, aligned with Self-Determination Theory, such as personal curiosity and a sense of competence. These internal drivers were strongly reinforced by behavioral anchors embedded within the platform's gamification mechanics, where features like streak systems, daily rewards, and interactive leaderboards effectively stimulated the students' competitive nature and routine-based commitment. Conversely, the study also identified that learning consistency remains highly vulnerable to external constraints, such as unstable internet connectivity, technological bugs, and system energy limitations, which temporarily disrupted the learners' behavioral control and created technical friction. The results of this study confirm that gamified mobile-assisted language learning (MALL) applications serve as vital motivational anchors that reinforce routine-based behavior. Educational institutions are suggested to provide structural support by integrating digital platforms into semi-structured literacy frameworks to maximize autonomous vocabulary acquisition. Finally, this study highlights the importance of balancing strong psychological drive with reliable technological support to cultivate sustainable digital autonomy among adolescent learners.742 English language and literature education798 Education technology2026-07-15Universitas Nusantara PGRI Kediri;KODEPRODI88203#Pendidikan Bahasa InggrisThesis

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