A Case Study of Code Mixing in an EFL Classroom
Evidence from an English Teacher in a Junior High School
Abstract
This study investigates the use of code mixing by an English teacher in an EFL classroom at SMPN 1 Kefamenanu, East Nusa Tenggara, Indonesia. The study aims to identify the types of code mixing employed, determine the dominant type, and explore the pedagogical reasons underlying its use during classroom interaction. A qualitative case study design was employed involving one English teacher teaching ninth-grade students in the academic year 2025/2026. Data were collected through non-participant classroom observation, audio recordings, and an open-ended questionnaire. Classroom interactions were transcribed and analyzed using Muysken’s typology of code mixing, which includes insertion, alternation, and congruent lexicalization. The findings revealed 55 utterances containing code mixing, consisting of insertion and alternation, while congruent lexicalization was absent. Alternation emerged as the dominant type, accounting for 43 utterances (78%), whereas insertion occurred in 12 utterances (22%). The teacher predominantly employed code mixing to facilitate comprehension, clarify instructional content, support students with limited vocabulary, maintain effective classroom communication, and create a more comfortable learning environment. The findings suggest that code mixing functions as a purposeful pedagogical strategy in multilingual EFL classrooms, particularly in contexts where students have limited English proficiency. This study contributes to sociolinguistic research on classroom discourse by providing empirical evidence from a junior high school context in Eastern Indonesia, which remains underrepresented in previous studies.
References
Asani, F. R., Abduh, A., & Muliati, A. (2024). Exploring code-switching and code-mixing in English and Indonesian language used by EFL teachers in classroom interaction. Pinisi Journal of Art, Humanity & Social Studies, 4(2), 475–487. Retrieved from https://journal.unm.ac.id/index.php/PJAHSS/article/download/1823/1130
Asmoro, M. P., & Annaningtyas, C. (2023). Analysis of code mixing used by Livy Renata in Tema Indonesia Youtube Channel. Radiant Journal of Applied, Social, and Education Studies, 4(1), 63–73. https://doi.org/10.52187/rdt.v4i1.127
Astri, Z., & Fian, A. (2020). The sociolinguistics study on the use of code mixing in Gita Savitri Devi’s Youtube channel video. Scope of English Language Teaching, Literature and Linguistics, 3(2), 83–92. https://doi.org/10.46918/seltics.v0i0.728
Datta, S. (2025). Code-mixing in class and communication: A dimension of translanguaging at the tertiary-level in Bangladesh. International Journal of Language Instruction, 4(4), 83–107. https://doi.org/10.54855/ijli.25446
Fadliyah, R., Dollah, S., & Muhayyang, M. (2023). An analysis of code mixing used by EFL students in the classroom presentation. ARRUS Journal of Social Sciences and Humanities, 3(4), 416–429. https://doi.org/10.35877/soshum1905
Hanafiah, R., Rantika, A., & Yusuf, M. (2018). The levels of English-Arabic code-mixing in Islamic boarding school students’ daily conversation. Advances in Language and Literary Studies, 9(6), 78–81. https://doi.org/10.7575/aiac.alls.v.9n.6p.78
Haryati, H., & Prayuana, R. (2020). An analysis of code-mixing usage in WhatsApp groups conversation among lecturers of Universitas Pamulang. Ethical Lingua: Journal of Language Teaching and Literature, 7(2), 236–250. https://doi.org/10.30605/25409190.180
Karubaba, S., & Rahman, F. (2025). Code-switching and code-mixing in Indonesian EFL classrooms : Teacher-student interactions in north Biak. Dialectica Online Publishing, 1(1), 107–115. https://doi.org/10.34050/dopj.v1i1.130296
Le, T. T. V. (2021). The phenomenon of code-mixing as practised in online newspapers for Vietnamese youth and the issue of preserving the purity of Vietnamese. International Journal of Innovation, Creativity and Change, 15(5), 762–771. Retrieved from https://www.ijicc.net/images/Vol_15/Iss_5/15549_Thuy_2021_E1_R.pdf
Matin, M. F., & Rozak, R. R. (2026). Code switching and code mixing used by students in an English classroom. Academy of Education Journal, 17(1), 153–161. Retrieved from https://jurnal.ucy.ac.id/index.php/fkip/article/view/3408
Mawonga, S. (2026). Bilingualism for teaching and learning: Exploring glossaries at an English-medium university in South Africa. Ikala, 31(1), 1–18. https://doi.org/10.17533/udea.ikala.356129
Melansari, N., Wahyuni, A., Adu, B., & Narni, N. (2023). Code mixing used by the teacher in teaching English at SMP Negeri 14 Baubau. International Journal of Education, Language, Literature, Arts, Culture, and Social Humanities, 1(1), 14–28. https://doi.org/10.59024/ijellacush.v1i1.22
Nurdiana, F., Arid, M., Wahyudi, W., & Marhum, M. (2026). The role of code-mixing in TikTok content : How mixed language videos affect students ’ vocabulary growth at SMAN 1 Sojol. Journal of General Education and Humanities, 5(1), 1059–1070. https://doi.org/10.58421/gehu.v5i1.1089
Pratiwi, I. E., Rahmawati, E., & Sa’diah, S. (2023). An analysis of Indonesian-English code-mixing found in Banten. Journal of English Language Teaching and Literature (JELTL), 6(2), 202–213. https://doi.org/10.47080/jeltl.v6i2.2798
Pratiwi, N. I., Sosrohadi, S., Rahman, F., Dalyan, M., Andini, C., & Muliyani, M. (2026). The use of code mixing by edu-influencers in social media: A communication strategy in sociolinguistic perspective. International Journal of Research and Innovation in Applied Science, 11(1), 1034–1042. https://doi.org/10.51584/IJRIAS
Purnamasari, N. M. G., Putra, I. N. A. J., & Suwastini, N. K. A. (2016). A descriptive study on the use of code mixing by the English teacher at SMAN Bali Mandara in the academic year 2014/2015. Lingua Scientia, 23(2), 1–8. https://doi.org/10.23887/ls.v23i2.16070
Putri, L. P. S. E., Claria, D. A. K., & Umiyati, M. (2024). Code mixing used by the teachers in teaching English at Dharma private English course. PRAGMATICA : Journal of Linguistics and Literature, 2(1), 9–19. https://doi.org/10.60153/pragmatica.v2i1.54
Rahmat, A. (2020). Code mixing in EFL classroom: Views from English teachers side. Al-Lisan: Jurnal Bahasa, 5(2), 130–147. https://doi.org/10.30603/al.v6i2.1323
Sakina, S. A., & Haryanto, S. (2025). Language using of code-mixing in captions and comments on instagram’s content creators. Acuity: Journal of English Language Pedagogy, Literature, and Culture, 11(1), 1–7. https://doi.org/10.35974/acuity.v11i1.4249
Samola, N. F., Mamentu, A. C., & Kemur, V. C. (2023). An analysis of English-Indonesian code-mixing used by Marion Jola. Proceedings of the Unima International Conference on Social Sciences and HUmanities, 1461–1470. Atlantis Press SARL. https://doi.org/10.2991/978-2-494069-35-0_176
Santosa, T. R., Sakina, R., & Kulsum, E. M. (2023). An analysis of code-mixing and code-switching used by an English teacher and students in EFL classroom in Sumedang. Gunung Djati Conference Series, 28, 88–99. Retrieved from https://www.conferences.uinsgd.ac.id/index.php/gdcs/article/view/1812/1259
Sari, N. F. (2022). Code switching and code mixing in classroom presentation of Indonesian EFL students. EDUCASIA: Jurnal Pendidikan, Pengajaran, Dan Pembelajaran, 7(2), 91–120. https://doi.org/10.21462/educasia.v7i2.71
Sepioł, A. (2025). Bilingualism, cognitive flexibility, and educational outcomes in young learners: Exploring the benefits of early language acquisition. Journal of Language and Culture in Education, 2(February), 62–75. https://doi.org/10.5281/zenodo.14724847
Sitinjak, A. S., Pakpahan, C., & Saragi, C. N. (2026). Code switching and code mixing in classroom interaction among fifth-semester English education student. JKIP: Jurnal Kajian Ilmu Pendidikan, 7(3), 1176–1195. Retrieved from https://journal.al-matani.com/index.php/jkip/article/view/2168/1332
Syafryadin, S., & Haryani, H. (2020). An analysis of English code mixing used in Indonesian magazine. Journal of Languages and Language Teaching, 8(4), 381–390. https://doi.org/10.33394/jollt.v8i4.2465
Utami, S., & Andharu, D. (2025). Code mixing practices in Indonesian language learning by class VII teachers of Junior High School 45 of Surabaya. Research and Development in Education (RaDEn), 5(1), 585–592. https://doi.org/10.22219/raden.v5i1.40566
Wagner, D., Bialystok, E., & Grundy, J. G. (2022). What is a language? Who is bilingual? Perceptions underlying self-assessment in studies of bilingualism. Frontiers in Psychology, 13, 1–12. https://doi.org/10.3389/fpsyg.2022.863991
Wahyuni, S., Aeni, N., & Hasriani, G. (2023). Teachers’ perceptions about the use of code-mixing in teaching English. Journal of Excellence in English Language Education, 2(2), 142–152. Retrieved from https://eprints.unm.ac.id/30555/1/4. Teachers_ Perceptions about the Use.pdf
Wardhana, I. G. N. P., Membrasar, G. I., Dewi, N. L. D. S., & Novi, U. G. W. (2023). Analysis of code mixing and code switching in teaching-learning process in kelas internasional-Net TV. International Journal of Linguistics and Discourse Analytics, 4(2), 94–101. Retrieved from https://www.ijolida.denpasarinstitute.com/index.php/ijolida/article/view/75/61
Wulandahri, D., Ilma, R., & Desvitasari, D. (2025). Navigating language alteration: A case study on English language teachers’ code switching and mixing in classroom speaking activities. Edukasi: Jurnal Pendidikan Dan Pengajaran, 12(2), 731–746. Retrieved from http://jurnal.radenfatah.ac.id/index.php/edukasi
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