SUKOHARJO, Indonesia — Learning English vocabulary through Duolingo can significantly improve students' vocabulary mastery while making classroom learning more engaging and enjoyable, according to a new study by Nawang Wulandari and Veronika Unun Pratiwi from Universitas Veteran Bangun Nusantara , Indonesia. Published in 2026 in the International Journal of Applied Educational Research (IJAER), the research found that integrating the popular language-learning application into classroom instruction substantially improved vocabulary achievement, classroom participation, and students' motivation to learn English.
The findings highlight how digital learning platforms can address one of the biggest challenges faced by vocational high school students: limited English vocabulary. For students preparing to enter the workforce, vocabulary is more than an academic requirement—it is the foundation for effective communication, reading technical materials, understanding workplace instructions, and interacting in an increasingly global job market.
Why Vocabulary Still Remains a Challenge
Although English is a compulsory subject in Indonesian schools, many vocational students continue to struggle with basic vocabulary. Limited vocabulary often prevents them from expressing ideas, understanding classroom instructions, and participating confidently in English lessons.
The researchers observed these challenges among students in Class XI BC 1 at SMK Veteran 1 Sukoharjo. Many students relied on Indonesian words when speaking English, hesitated to answer questions, and found it difficult to understand classroom tasks delivered in English. Traditional learning materials, including printed worksheets, were no longer sufficient to keep students actively engaged.
Recognizing these challenges, the research team explored whether a technology-based learning tool could create a more interactive and motivating learning experience.
Bringing Duolingo into the Classroom
Instead of replacing classroom instruction, Duolingo was used as a supplementary learning platform during English lessons.
The study involved 37 eleventh-grade students and followed a Classroom Action Research design conducted over two learning cycles during the 2025/2026 academic year. Students completed vocabulary activities through Duolingo while teachers monitored their progress, provided guidance, and refined instructional strategies after each learning cycle. Researchers evaluated students using vocabulary tests, classroom observations, interviews, and questionnaires to measure both academic progress and learning behavior.
Vocabulary Scores Improved Significantly
The most notable finding was the consistent improvement in students' vocabulary achievement throughout the research.
Average vocabulary scores increased from:
- 64.6 in the pre-test,
- to 73.7 after the first learning cycle,
- and reached 80.3 after the second cycle.
Student mastery also improved considerably. Before Duolingo was introduced, only 35.1% of students achieved the school's minimum competency standard. After the first cycle, the percentage increased to 54.0%, and by the end of the second cycle it had reached 75.6%.
According to the researchers, the gradual improvement demonstrates that students became more successful as they grew familiar with the application and as classroom instruction was continuously refined.
Students Became More Active and Confident
The benefits extended beyond higher test scores.
Classroom observations revealed noticeable improvements in student participation, confidence, motivation, and enthusiasm. The overall observation score increased from 67.2% during the first cycle to 85.4% during the second cycle. Students became more willing to answer questions, follow teacher instructions, participate in classroom discussions, and complete learning activities independently.
Researchers noted that Duolingo's gamified learning environment encouraged students to view vocabulary practice as an enjoyable challenge rather than a stressful classroom task.
Gamification Keeps Students Motivated
One reason behind the improvement appears to be Duolingo's game-based learning design.
Rather than memorizing vocabulary lists, students earned points, progressed through levels, completed daily challenges, and received immediate feedback after each exercise. These features created a sense of achievement that encouraged students to continue practicing.
Student feedback strongly supported these observations. The questionnaire revealed an overall positive response rate of 82.03% toward using Duolingo in English lessons. The highest-rated feature was the application's gamification system—including points, levels, and challenges—which received an approval rating of 87.16%. Students also reported that Duolingo helped them understand word meanings more effectively and made vocabulary learning more enjoyable.
More Than Better Test Scores
According to Nawang Wulandari and Veronika Unun Pratiwi of Universitas Veteran Bangun Nusantara, the findings suggest that digital learning applications can improve both academic performance and students' attitudes toward learning. Their research indicates that repeated vocabulary practice, immediate feedback, and engaging game-like activities encourage students to become more active, confident, and motivated during English lessons.
Importantly, the researchers emphasize that Duolingo should complement—not replace—the role of teachers. Teacher guidance remained essential throughout the learning process by providing explanations, monitoring progress, and encouraging students to apply new vocabulary in meaningful classroom activities.
Implications for Schools
The study offers practical insights for English teachers seeking innovative ways to improve vocabulary instruction, particularly in vocational education where practical communication skills are essential.
For schools, integrating accessible digital platforms like Duolingo can create a more interactive learning environment while increasing student motivation. For education policymakers, the findings provide evidence that technology-supported instruction can strengthen language learning without fundamentally changing the existing curriculum.
As digital learning continues to expand across Indonesian schools, the study demonstrates that combining classroom instruction with well-designed educational technology may help students develop stronger language skills and greater confidence for future academic and professional success.
Author Profiles
Nawang Wulandari is a researcher from Universitas Veteran Bangun Nusantara, Indonesia, whose research focuses on English language teaching, vocabulary development, classroom action research, and technology-assisted learning.
Veronika Unun Pratiwi is a lecturer and researcher at Universitas Veteran Bangun Nusantara, Indonesia, specializing in English education, language teaching methodology, educational technology, and applied linguistics.
Source
Article Title: Improving Students' Vocabulary By Using Duolingo at SMK Veteran 1 Sukoharjo: A Classroom Action Research of the XI BC 1 of SMK Veteran 1 Sukoharjo in the Academic Year 2025/2026
Authors: Nawang Wulandari and Veronika Unun Pratiwi
Journal: International Journal of Applied Educational Research (IJAER)
Publication Year: 2026
DOI: https://doi.org/10.59890/ijaer.v4i3.6
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