The particular dialect or language that a person chooses to use on any occasion is called a code 838 Copyright Β© 2025 The Author IDEAS is licensed under CC-BY-SA 4.0 License Issued by English study program of IAIN Palopo IDEAS Journal of Language Teaching and Learning, Linguistics and Literature ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) Volume 13, Number 1, June 2025 pp.838 - 850 Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School Dina Navisa D. Agusalim1, Abdul Kamaruddin2, Wahyudin3, Mawardin M. Said4 1,2,3,4Pendidikan Bahasa Inggris, FKIP Universitas Tadulako E-mail: navisadina60@gmail.com Received: 2024-12-02 Accepted: 2025-05-27 DOI: 10.24256/ideas. v13i1.5897 Abstract The objective of the research is to ensure whether or not employing code mixing can improve English vocabulary of grade VIII students at SMP Negeri 15 Palu. The population of this research was the eighth grade students at SMP Negeri 15 Palu. Researcher selected sample using purposive sampling technique. The sample of this study were students of class VIII B as an experimental class totaling 31 students and class VIII C as a control class totaling 33 students. The data were analyzed statistically to determine the significant difference of students achievement in pre-test and post-test. The mean score of the experimental class on the pretest was 42.19 and the control class was 43.39. Th mean score of the experimental class on posttest was 78.70 and control class was 44.72. By using 0.05 level of significance and 62 degree of freedom, the researcher get the result t-counted (9.11) was higher than t-table (1.657). It means that the hypothesis is accepted. In conclusion, the use of code mixing can improve English vocabulary of grade VIII students at SMP Negeri 15 Palu. Keywords: Improving, English Vocabulary, Code Mixing Introduction English is a universal language because it is the primary language of most countries around the world. Furthermore, English is one of the most important international languages to understand or learn. In Indonesia, English is seen as a foreign language, yet it occupies an important position in our society. This is evident in the world of education in Indonesia. English is one of the subjects taught to students from elementary school to university level. However, when you want to learn English, the most important first step to learn is vocabulary. http://u.lipi.go.id/1457703302 mailto:navisadina60@gmail.com IDEAS, Vol. 13, No. 1, June 2025 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 839 Vocabulary is the list of words that a person has and understands in a language, which includes various types of words, such as general words, specialized terms, and phrases. The challenges of learning English according to research from Nurhaliza, S., et al. (2024) include students not understanding what is discussed by the teacher during the learning process, unsupportive facilities, and the influence of the surrounding environment, one of which is friends. Learning English vocabulary is very important for junior high school students because a rich vocabulary is the basis for effective communication skills. At this age, students begin to interact more in academic and social contexts, so mastery of vocabulary helps them understand lessons, participate in discussions and express ideas clearly. During the researcher observed of some students in the VIII grade at SMP Negeri 15 Palu, some of them experienced problems in learning English. Some of these problems were memory limitations, lack of practice when finding new vocabulary, difficulty in making sentences, students not using dictionaries when studying and shyness or lack of confidence. Those are some of the obstacles experienced by some students. Therefore, students feel insecure, have difficulty in remembering new vocabulary due to lack of practice, and have difficulty responding to the teacher questions. Thus, effective strategies are needed to improve students' English vocabulary, one of which is code-mixing to train students by inserting English words into the context of daily language use, students can more easily remember new vocabulary. The vocabulary becomes more meaningful because it is connected to students' experiences. Code mixing can be an effective solution to overcome various challenges in learning English vocabulary at the junior high school level, such as limited recall of new vocabulary, lack of practice, and difficulty in making sentences. By using code- mixing, teachers can explain new vocabulary in a language that is more familiar to students, such as Indonesian, thus helping them remember it more easily. In addition, code-mixing allows students to practice constructing sentences with more confidence, starting with simple sentences in Indonesian and gradually adding English vocabulary. It also reduces students' anxiety when speaking in English, as they know they can use Indonesian to explain if needed. With this approach, students can more actively use vocabulary in real conversations, accelerating comprehension and increasing their engagement in the learning process. Speaking in two languages at once is known as "code mixing" (English and Indonesian). Code mixing is the practice of combining language units owned by one language with language units owned by another language in order for the speaker's language variety or style to develop (Ferdianto, 2020). This method can assist students in learning the etymologies of English words and aid in vocabulary retention. Students are directed to memorize vocabulary in a more relaxed way by using this strategy, which actively engages their brains. Students are encouraged to Dina Navisa D. Agusalim, Abdul Kamaruddin, Wahyudin, Mawardin M. Said Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School 840 engage in the learning process by utilizing active learning techniques. The code mixing technique was selected by the researcher because it helps students learn to use more vocabulary in English. Code mixing is a common occurrence in everyday life. Mixing two codes or two languages without changing the context is referred to as code mixing. Code mixing is most common in sentences. According to Al-Ahdal (2020), code-mixing is a phenomenon that occurs in linguistic communication when someone uses one language while using another language. Code mixing is commonly used in everyday life because there are many languages that can be used in society, such as Kaili, Javanese, Bugis, Indonesian, English languages, and others. Most people mix their language with other languages by incorporating elements of the second language, which is sometimes still influenced by the first. In relation to the discussion of more than one language, the term bilingual is used. Bilingual is an ability that a person has in terms of using and mastering more than one language. People who have the ability and master more than one language such as local languages, Indonesian and foreign languages, and are accustoming to using these languages can be said to be "bilingualism", while people who have the ability and master more than one language such as local languages, Indonesian and foreign languages, but do not have the opportunity and are not accustoming to using these languages can be said to be "bilinguality". There are several studies related to the use of code mixing in English language learning to improve vocabulary. One of them comes from the research of Putri et al. (2024) entitled Code Mixing Used by The Teachers in Teaching English at Dharma Private English Course. The result of their research is utilizing a mixture of local language and English in teaching is an effective method for instructing students in English language acquisition. It allows students to comprehend word pronunciation and become accustomed to listening to English. However, teachers must employ code-mixing judiciously, in accordance with the needs and abilities of the students. This research can be conducted to all junior high school students. So it is likely that if the same research is carried out, it will get the same results as the current research. Because the researcher realizes that there are still many shortcomings in this study, in the end the results of this study are effective in improving students' English vocabulary. One of the key components of learning English is expanding one's vocabulary, which facilitates speaking and writing. In actuality, a number of factors become barriers to reaching learning objectives, such as some of these problems were memory limitations, lack of practice when finding new vocabulary, difficulty in making sentences, students not using dictionaries when studying and shyness or lack of confidence. The researcher formulated the research question, namely: Can the use of code mixing improve English vocabulary of grade VIII students of SMP Negeri 15 Palu? IDEAS, Vol. 13, No. 1, June 2025 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 841 Based on this research entitled Improving English Vocabulary of Grade VIII Students at SMP Negeri 15 Palu. The researcher made a chart of the learning model using code mixing technique. It can be seen in the following chart: Conceptual Framework Most students lack speaking practice when finding new vocabulary Part of Speech Noun Adjective Pronoun Verb Adverb Interjection Conjunction Preposition Improving Code Mixing Teaching Learning Teacher Students Vocabulary Dina Navisa D. Agusalim, Abdul Kamaruddin, Wahyudin, Mawardin M. Said Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School 842 Method The researcher applied the quasi-experimental design method in this study. The same test was given to both classes, but only one class received treatment or participated in the experiment which is class VIII B, while class VIII C only be the control class. This research design refers to the opinion of Arikunto (2013). The researcher used tests as research instrument. Pretest and posttest are the names of two parts of the test. A pretest was given before the treatment to test the students' English vocabulary ability. The researcher instruct the students to improve their vocabulary based on the given material. After six treatment, the researcher given the posttest after the treatment to the students to compare the result of each test before and after the treatment. In this study, the treatment was conducted after conducting the pre-test. This activity was carried out during English class hours according to the school schedule. The time required during the treatment is 3 lesson hours. The material used is in accordance with the learning material at school, namely using the "English For Nusantara class VIII" package book. The following is the learning process in the classroom conducted by researcher in several meetings: ➒ Experimental class 1. The researcher gave the students a litle time to pray. 2. The researcher checked the students' attendance. 3. The researcher explained the purpose of the researcher's goal, namely to improve English vocabulary through the use of code mix. 4. Asked students to make groups. 5. The researcher instructed the students to open the topic page that had been determined in the package book and explained the topic. 6. Students were asked to observe the pictures or illustrations in the book. Then the researcher ordered the students to look for any words in the picture. 7. The researcher gave an example and then followed by students looking for several words. 8. Students discussed the new words they found. 9. Students are asked to make sentences about the topic they have learned using the new words they found. 10. Students present their work using code mixing so that the researcher can measure the level of achievement of students' understanding. 11. After finishing the lesson, the researcher asked students whether there were any difficulties in learning English during the learning time given and provided solutions or motivation to students. IDEAS, Vol. 13, No. 1, June 2025 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 843 ➒ Control class 1. Ensure that the control class only receives standard teaching without any special treatment. 2. Use the same materials as the experimental class, without any additions. 3. Set the same schedule as the experimental class which is 6 meetings. 4. Observe students' development during the learning process. Results In this research, the researcher provides data from the research that has been done to see the improvement of students' vocabulary. Data collection was conducted in August 2024 of grade VIII at SMP Negeri 15 Palu. The research instrument used were pre-test and post-test. Researcher used two classes, namely class 8 B as the experimental class and class 8 C as the control class. Table 1 Students score of the experimental class No Initials Students scores Deviation (𝑋2βˆ’π‘‹1) Square deviation (π‘₯2) Pre-test (𝑋1) Post-test (𝑋2) 1 AA 36 72 36 1296 2 AAK 48 80 32 1024 3 AI 36 76 40 1600 4 AP 56 60 4 16 5 AR 44 76 32 1024 6 ARS 52 92 40 1600 7 FA 48 64 16 256 8 FE 52 76 24 576 9 FR 48 92 44 1936 10 FY 32 84 52 2704 11 IPR 32 72 40 1600 12 KA 52 80 28 784 13 LPM 28 68 40 1600 14 MA 52 88 36 1296 15 MHS 36 72 36 1296 16 MJ 44 84 40 1600 17 MN 36 84 48 2304 18 MR 48 84 36 1296 19 MRP 16 64 48 2304 Dina Navisa D. Agusalim, Abdul Kamaruddin, Wahyudin, Mawardin M. Said Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School 844 20 NA 24 64 40 1600 21 N 56 64 8 64 22 NN 28 88 60 3600 23 PR 28 80 52 2704 24 QJ 40 72 32 1024 25 RAM 52 80 28 784 26 RAP 60 88 28 784 27 RKL 48 84 36 1296 28 RS 52 88 36 1296 29 SA 60 96 36 1296 30 SAH 20 72 52 2704 31 S 44 96 52 2704 TOTAL 1308 2440 1132 1281424 MEAN 42,19 78,70 36.51 Table 2 Students scoreof the control class No Initials Students scores Deviation (𝑋2βˆ’π‘‹1) Square deviation (π‘₯2) Pre-test (𝑋1) Post-test (𝑋2) 1 A 32 36 4 16 2 AF 32 52 20 400 3 AM 56 52 -4 16 4 ANA 60 56 -4 16 5 ES 32 44 12 144 6 GZ 44 44 0 0 7 I 12 16 4 16 8 IWPM 56 52 -4 16 9 K 44 48 4 16 10 MAAR 56 56 0 0 11 MD 36 36 16 256 12 MF 52 60 8 64 13 MH 40 32 -8 64 14 M 44 36 -8 64 15 MN 60 52 -8 64 16 MRSQ 16 20 4 16 17 MSY 52 52 0 0 IDEAS, Vol. 13, No. 1, June 2025 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 845 18 MS 52 48 -4 16 19 NA 52 48 -4 16 20 NIP 40 44 4 16 21 NPR 28 36 8 64 22 NSR 48 28 -20 400 23 NW 52 52 0 0 24 RF 56 52 -4 16 25 RIO 40 28 -12 144 26 RJ 28 48 20 400 27 RPA 24 28 4 16 28 RS 44 56 12 144 29 RSA 48 56 8 64 30 S 48 44 -4 16 31 SAP 28 44 16 256 32 W 52 36 -16 256 33 ZH 68 68 0 0 TOTAL 1432 1476 44 2992 MEAN 43.39 44.72 1.33 After knowing the results of the experimental class and control class, the researcher calculated the square deviation using the formula proposed by Arikunto (2013, p. 355): Experimental class βˆ‘ 𝑋2 = βˆ‘ 𝑋2 βˆ’ (βˆ‘π‘‹)2 𝑁 βˆ‘ 𝑋2 = 1281424 βˆ’ (1132)2 31 βˆ‘ 𝑋2 = 1281424 βˆ’ 1281424 31 βˆ‘ 𝑋2 = 1281424 βˆ’ 4133625 βˆ‘ 𝑋2 = 12400.88 Control class βˆ‘ π‘Œ2 = βˆ‘ π‘Œ2 βˆ’ (βˆ‘π‘Œ)2 𝑁 βˆ‘ π‘Œ2 = 2992 βˆ’ (44)2 33 Dina Navisa D. Agusalim, Abdul Kamaruddin, Wahyudin, Mawardin M. Said Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School 846 βˆ‘ π‘Œ2 = 2992 βˆ’ 2992 33 βˆ‘ π‘Œ2 = 2992 βˆ’ 90.66 βˆ‘ π‘Œ2 = 2901.34 Based on the result above, it can be presented that the squared deviation the score of the experimental group is 12400.88 and the score ia the squared deviation of the control group is 1877.34. furthemore, the researcher applied the t-count formula. This a formula is used to indicate how effective the treatmeant is. Researcher use the formula proposed by Arikunto (2013,p.354): t = Mx βˆ’ My √( βˆ‘x2 + βˆ‘y2 Nx + Ny βˆ’ 2) ( 1 Nx) ( 1 Ny) t = 36 βˆ’ 1 √( 12400.88 + 2901.34 31 + 33 βˆ’ 2 ) ( 1 31) ( 1 33) t = 35 √( 15302.22 62 ) ( 1 31) ( 1 33) t = 35 √(246.81) ( 64 1023) t = 35 √(246.81) (0.06) t = 35 √14.8 t = 35 3.84 t = 9.11 In order to know whether the hypothesis is accepted or rejected, the researcher needed to test it based on the result of the data analysis. If the t-count is higher than the t-table, then the hypothesis is accepted. This study accepts that the use of code-mixing has a significant effect on students' vocabulary improvement. Meanwhile, if the t-count is smaller than the t-table, it means that the hypothesis in this study is rejected or the use of code-mixing does not have a significant effect on students' vocabulary improvement. To determine whether the hypothesis was accepted or rejected, the researcher did the following calculation: IDEAS, Vol. 13, No. 1, June 2025 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 847 Degree of freedom (df) = Nx + Ny – 2 = 31 +33 -2 = 62 ( 60-120 ) Level of significant = 0,05 40 = 1.684 60 = 1.671 π‘Ž 𝑏 π‘₯ 𝑐 Where : a = the value of the amount of the students subtract with the df (60) b =the value of the df (120) subtract with the df (60 ) c= the value of value df (60) subtract with the value of df (120) a = 62 -60 = 2 b = 120-60 = 60 c = 1671 – 1658 = 13 π‘Ž 𝑏 π‘₯ 𝑐 = 2 60 π‘₯ 13 = 0.43 Df (62) = 1658 – 0.43 𝑑 βˆ’π‘‘π‘Žπ‘π‘™π‘’= 1.657 The results of the data analysis showed that the t-count is 9.11. Then, using a significance level of 0.05 with degree of freedom (df = 62), the researcher found that (t-count = 9.11) is higher than (t-table = 1.657). This shows that the hypothesis in this study is successful or accepted. In short, the use of code mixing can improve students' vocabulary of grade VIII at SMP Negeri 15 Palu. Discussion This research decided differences between previous studies. Starting off, previous research used qualitative, meanwhile this study employed quantitative methods with pre-test and post-test instruments. Then, there are differences in research location and time. The similarity with previous research is the use of code mixing during English language learning. In a research that directed students to use code mixing for six meetings to improve their English vocabulary, the researcher applied an approach that encouraged students to combine Indonesian and English in the learning process. At each meeting, the researcher instructed them to look up a word in English, then asked the students to try to use the word in a sentence by adding Indonesian elements if needed. For example, when learning the word "independence" in English, the researcher can direct students to make sentences such as, "every 17th of august ditetapkan sebagai independence day". Dina Navisa D. Agusalim, Abdul Kamaruddin, Wahyudin, Mawardin M. Said Improving English Vocabulary of Grade VIII Students Through Code Mixing at Junior High School 848 During the six meetings, the researcher encouraged the students to use Indonesian as a bridge so that they could remember and apply the English vocabulary more quickly in daily conversations. They pronounce the word, spell the word and say the meaning of the word. In this way, it can help students remember new vocabulary in a more natural way, and reduce the fear of speaking incorrectly. Although the first meeting they felt a little confused, especially if they were not familiar with the concept. However, as time goes by, they can feel more confident in improving their vocabulary. The researcher encountered obstacles when giving the treatment, such as some students did not bring dictionaries when learning English and also did not have other translation aids such as cellphones that could access translator websites and some other students were not confident in their vocabulary pronunciation. However, the researcher looked for ways to keep the learning running smoothly by instructing students to work in groups or discussions, the researcher utilized audio media for students to listen to the correct pronunciation of vocabulary and also pronounce the words together. In this way, no student felt cornered because the experimental class students received the same treatment from the researcher. The researcher provides some suggestions for improvement in the teaching and learning process, especially in vocabulary. First, teachers should create a classroom environment that requires students to use English. Second, the teacher can ask students to make sentences or stories using the newly learned vocabulary. This helps students understand the meaning of words and how to use them in everyday situations. Finally, the researcher hopes that this study can be useful and interesting for other researchers who want to conduct similar research and can be a reference for them. Conclusion The use of code mixing can improve students' vocabulary. It is proven by the significant difference between the average score of Pretest is 42.19 and Posttest is 78.70. The results showed that the t-count was 9.11 higher than the t-table value of 1.657, proving that the hypothesis was accepted and there was an improvement in students' English vocabulary pronunciation after the researcher gave the treatment. In other words, the use of code mixing has a positive effect on English learning in improving vocabulary. 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