The particular dialect or language that a person chooses to use on any occasion is called a code 2204 Copyright © 2024 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 12, Number 2, December 2024 pp. 2204 - 2220 YouTube Video in Improving Senior High Students’ Vocabulary Mastery Andi Rachmawati Syarif1, Faridawati2, Nurfadilla3 Syahriani4 rachmasyarif@gmail.com1, Faridawat@umkendari.ac.id2, nurfadilla.13@umkendari.ac.id3, ririn@umkendari.ac.id4 1,2,3,4English Education, Faculty of Teacher Training and Education, Muhammadiyah University of Kendari Received: 2024-07-04 Accepted:2024-12-31 DOI: 10.2456/ideas. v12i2.5223 Abstract The study aims to investigate the practical implications of using YouTube videos to improve the vocabulary mastery ability of students in class X RPL B (Rekayasa Perangkat Lunak) SMK Negeri 4 Kendari. The researcher used a pre-experimental research method using one group pre-test and post-test design. The sample of this study was 30 class X students from the RPL B department of SMK Negeri 4 Kendari. The data collection instruments used in this study were pre-test and post-test. Based on the results of the data analysis, the average pre-test score was higher than the post-test, with a pre-test of 54.78 and a post-test of 81.44. Based on the results of statistical calculations using paired sample t-test, the standard deviation value was 10.47 with a significance level of 0.000. Thus, it can be assumed that Ha is accepted, which indicates a significant increase in students' comprehension ability before and after learning using YouTube videos. Therefore, it can be concluded that the application of YouTube videos effectively improves the comprehension ability of class X RPL B students of SMK Negeri 4 Kendari in the 2023/2024 academic year, providing practical insights for language educators and stakeholders. Keywords: Students’ Vocabulary Mastery, YouTube Video Introduction One important aspect of language learning is mastery of the vocabulary of the target language. Experts say that mastery of vocabulary is very important for students. This is more than just grammar for communication purposes. (Amanda et al., 2023). Vocabulary is an important component of language learning (Kabooha&Elyas, 2015). Vocabulary is an initial stage that must be studied and mastered by students because students will find it difficult to learn more about the main language of English if students do not know and master a lot of vocabulary http://u.lipi.go.id/1457703302 mailto:rachmasyarif@gmail.com1 mailto:Faridawat@umkendari.ac.id2 mailto:nurfadilla.13@umkendari.ac.id3 mailto:ririn@umkendari.ac.id4 IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2205 as a basis. (Maulana, 2023). Therefore, learning vocabulary becomes an important part of students in the language learning process. Regarding the importance of vocabulary, students learning a foreign language need to master the vocabulary of the language. Zahedia and Abdi (2012) state that "the capacity to comprehend meaning and employ words appropriately is associated with vocabulary mastery." Therefore, learning new terms in the language will be simpler for someone with a large vocabulary. Thornbury (2002) suggests that students should master at least 2000 words to interact with people in the neighborhood when learning a foreign language. This suggests that by mastering 2000 words, EFL learners can understand most of the daily conversations and can easily learn a foreign language. There are various problems related to vocabulary mastery and the level of language proficiency students demonstrate. One study conducted by Oljira (2017) in this study revealed that students who only have a small vocabulary are the main problem that causes them difficulty in constructing ideas in speaking and writing. This problem must be addressed immediately because students with poor vocabulary mastery will have difficulty continuing to the next level in learning a foreign language. Learning English will be a challenge if students do not have sufficient vocabulary. If students lack understanding and learn vocabulary, they will struggle to master other competencies. As the key to successful learning, teachers will have an important role. Therefore, teachers should emphasize improving students' vocabulary. There are several approaches to teaching vocabulary, and making studying engaging and enjoyable for children is one way to inspire them to increase their vocabulary. Teachers must be creative in creating a good and interesting classroom to teach vocabulary. According to Harmer (2007) and Maulana (2023) educators should consider technology as a tool that can assist them in implementing the teaching strategies and methods they have chosen. Utilizing technology or multimedia, such as audiovisual media or videos, is one of the recommended methods to make vocabulary teaching more entertaining. Technology can help teachers teach children vocabulary more engagingly and motivate them to acquire new phrases. YouTube is an online video service whose main goal is to provide a medium for searching, competing, and sharing original videos to and from all corners of the world via the web (Budiargo 2015, Auriana et al., 2021). YouTube is an audiovisual platform that can help students learn vocabulary in an entertaining way while also providing a variety of teaching materials that can be accessed from anywhere. Many researchers investigating second language acquisition have focused their attention on the impact of technological instruction on vocabulary improvement. Researchers have found evidence suggesting that learning a new language is facilitated by videos and pictures. According to Chun and Plass (1996) Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2206 and Maulana (2023), increasing vocabulary acquisition with graphic and verbal cues may help remember the studied lexical products. Research conducted by Al- Seghayer (2005, p.204) identified various settings of multimedia effects: "A definition of printed text only, a definition of printed text in relation to images, and a definition of printed text messages coupled with video". The study's findings indicated that watching videos with textual explanations would be a more engaging and significant way to acquire English vocabulary than looking for pictures and textual references. These are the conclusions drawn from this research. The older the video, the more language students can acquire and remember in research compared to when they are shown photos. Then research conducted by Wang and Chen (2020) in Taiwan regarding EFL students' independent language learning using YouTube outside of language class 20 students' responses were analyzed and showed that there was a special attraction for them when learning languages from watching YouTube, they felt that learning languages from YouTube was considered more flexible, interesting and interactive than normal learning in the classroom. Similarly, according to studies conducted by Hariyono (2020), Hia (2021), and Maulana (2023), using YouTube videos to teach English can improve language instruction in the classroom. Previous study has only looked at the broad benefits of YouTube video media as a tool for students' vocabulary development. This study aims to solve the ignored limits of previous studies by assessing the influence of YouTube videos on vocational high school students in Indonesia. While the researcher participated in the Teaching Assistance program (MBKM) at SMK Negeri 4 Kendari for 4 months (September 2023 - January 2024), especially in the first-year RPL (Rekayasa Perangkat Lunak) software engineering class, the researcher identified several students as having difficulty mastering vocabulary and even having a very minimal vocabulary. When the researcher taught an English teacher in this class, the researcher found that some students found it very difficult to remember their vocabulary, even the vocabulary they had learned last week. Researchers found several factors that caused this; students had less attention when learning English in class because students were more focused on their gadgets, which currently schools are implementing the Kurikulum Merdeka, and students are allowed to use gadgets during learning. This causes some of them to prefer playing games rather than paying attention to the lesson material, and besides that, English is not a mandatory subject, so the time available is only 2 hours a week. Based on the explanation above, it encourages researcher to choose one technique for teaching English using YouTube videos. The researcher's interest in choosing YouTube video media because the media is interesting to use, and the researcher wanted to apply this media in learning English in class X RPL B IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2207 (Rekayasa Perangkat Lunak) SMK Negeri 4 Kendari and see an increase in students' English vocabulary after using YouTube videos. Method This study used a mixed method. According to Cresswell and Clark (2008), mixed method research is a study strategy which combines both qualitative and quantitative data collection methods and is guided by philosophical assumptions. The researcher adopted the Explanatory Sequential Design as a mixed-methods approach. In this research methodology, data is collected sequentially rather than concurrently. The first level includes quantitative data, followed by qualitative data. This study used 30 students from SMK Negeri 4 Kendari's Software Engineering (Rekayasa Perangkat Lunak) department as the sample. The sample was the class that the researcher taught English to for 4 months as part of the teaching assistance program. The data were acquired using four different instruments: pre-test, treatment, post-test, and interview. The thirty pre-test and post-test questions, which were validated before being presented to students, included adjectives, prepositions, and action verbs. The three meetings treatment was carried out according to with a lesson plan developed in collaboration with the English teacher and researcher. Each treatment provided to students included two YouTube videos that related to the subjects discussed at the meeting. The video was approximately 5-10 minutes and included explanations and examples of the material to be presented that day. Students were given a post-test to determine their results following treatment. The interview was conducted at the end of the meeting. It aims to measure students' affection and feelings in learning vocabulary by using video media (YouTube). Semi-structured interviews were adapted in this study to provide accurate answers related to the scores obtained during the post-test. Data was obtained from the test results given to class X RPL B by a test conducted on the pretest-post-test. Before the test is given to students, the instrument must be tested first. Instrument testing is done with validity and reliability tests. Before conducting validity and reliability tests, pretest and posttest questions were tested first in class X BRF (Broadcasting and Film) department SMK Negeri 4 Kendari. Utilizing Pearson Product Moment correlation and statistical tests with SPSS 23.0 for Windows, determine the validity of each pretest and posttest item. The Cronbach Alpha test was utilized with the SPSS 23.0 for Windows application for the reliability test. The normality test and the paired sample t-test are the preparatory tests that come after the instrument test. Data from the population are subjected to data normality testing to ascertain whether or not they are normally distributed. The Shapiro-Wilk test is applied as a normality test because the sample size is less than fifty and the significance level is Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2208 0.05. After completing the prerequisite test, the next step is to conduct hypothesis testing. If the data is homogeneous and from a regularly distributed population, the Independent Sample T-Test is applied to test the hypothesis. If the significance value is more than 0.05, H0 is accepted, and H1 is rejected; otherwise, H0 is accepted, and H1 is rejected (Wahyono, 2012: 102). Result Validity Test and Reliability Test The data from the instrument trial were then tested for validity and reliability. Pretest and posttest questions were among the instruments that were validated before to the investigation. The findings of calculating the validity of the pre-test questions using SPSS 23.0 for Windows, which were initially assessed in class X BRF (Broadcasting and Film) SMK Negeri 4 Kendari, 30 students who took a pre-test of 30 questions will be tested for validity using SPSS 23.0 for Windows. The following validity data is shown below. Table 1. Validity Test Results of Pre-test Questions Question items Person Collection (𝑹𝒄𝒐𝒖𝒏𝒕) Sig. Value (α =0,05) 𝑹𝒕𝒂𝒃𝒍𝒆 (30) Conclusion 1 -0.679 0.000 0,3610 Valid 2 0.724 0.000 0,3610 Valid 3 -0.342 0.044 0,3610 Valid 4 0.703 0.000 0,3610 Valid 5 0.357 0.035 0,3610 Valid 6 0.596 0.000 0,3610 Valid 7 -0.412 0.014 0,3610 Valid 8 0.245 0.156 0,3610 Invalid 9 -0.172 0.323 0,3610 Invalid 10 0.086 0.623 0,3610 Invalid 11 -0.152 0.385 0,3610 Invalid 12 0.724 0.000 0,3610 Valid 13 0.126 0.470 0,3610 Invalid 14 0.248 0.151 0,3610 Invalid 15 -0.415 0.013 0,3610 Valid 16 0.415 0.013 0,3610 Valid 17 0.724 0.000 0,3610 Valid IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2209 18 -0.033 0.849 0,3610 Invalid 19 0.323 0.058 0,3610 Valid 20 -0.183 0.292 0,3610 Valid 21 0.724 0.000 0,3610 Valid 22 0.362 0.032 0,3610 Valid 23 0.412 0.014 0,3610 Valid 24 0.147 0.400 0,3610 Invalid 25 0.209 0.229 0,3610 Invalid 26 0.415 0.013 0,3610 Valid 27 0.110 0.528 0,3610 Invalid 28 0.703 0.000 0,3610 Valid 29 0.415 0.013 0,3610 Valid 30 0.703 0.000 0,3610 Valid On Tuesday, April 23, 2024, 35 students spent 90 minutes validating the pre- and post-tests. After evaluating the data using SPSS, the researcher discovered that 10 of the thirty items were invalid. Lecturers in English education have personally evaluated the 10 invalid questions, which are 8, 9, 10, 11, 13, 14, 18, 24, 25, and 27 and modified the structure of the questions and options for responding, which were very similar. The 20 valid question items can be used for further studies, whereas the 10 invalid items must be evaluated for validity and reliability. The instrument reliability test is the next test, and Table 2 below shows the results of the pretest question reliability test: Table 2. Reliability Test Results of Pre-test Questions Reliability Statistic Cronbach’s Alpha N of items 0,619 31 Table 2 shows that the range of Cronbach Alpha values is between 0.60 and 0.90. The table shows that the Cronbach Alpha value is 0.619 from the question data that has previously been checked for validity. The results show that the question items have a Cronbach Alpha value of 0.619 which means that the value is in the reliable category to be used as pre-test data. Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2210 Analysis Descriptive Based on observations in the field while carrying out research and from the results obtained from data processing that has been tested through statistical analysis, statistical data on student learning outcomes in experimental classes calculated from research data according to the table can be presented. Table 3. Classification on Students' Score of Pre-test and Post-test Value Classification Pre-test Post-test Frequency Percentage Frequency Percentage 80- 100 Very good 4 13,33% 20 66,67% 70-79 Good 5 16,67% 4 13,33% 60-69 Fair 2 6,67% 4 13,33% 50-59 Low 7 23,33% 2 6,67% 0-49 Very low 12 40% 0 0% Total 30 100% 30 100% The pre-test was given on Friday, April 26, 2024. This pre-test aims to determine students’ initial knowledge before using YouTube videos to enhance their vocabulary mastery. Based on the pre-test outcomes, the range of student scores revealed that one student obtained the highest score of 86.6 and the lowest score of 23,3. The pre-test results for the thirty students are displayed in Table 3. There were 4 students (13.33%) were rated as "very good," 5 (16.67%) as "good," 2 students (6.67%) as "fair," 7 students (23.33%) as "low," and 12 students (40%) as "very low" The pre-test outcomes revealed that the majority of students in the X RPL B class have very low vocabulary achievement. The post-test was given on Monday, May 13, 2024. The researcher utilized a post-test to evaluate students' development in vocabulary mastery after using YouTube videos as a therapy technique. Based on the post-test results, the range of student scores revealed that one student achieved the highest score of 100 and the lowest score of 53.33. The post-test results for the thirty students are displayed in Table 3. There were 20 students (66.67%) who were categorized as "very good" criterion, 4 students (13.33%) as "good," 4 students (13.33%) as "fair," 2 students (6.67%) as "low," and 0 students (0%) as "very low." According to the post-test results, the use of YouTube videos influences students' vocabulary acquisition and achievement. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2211 Table 4. Classification Diagram Table Student’s Score of Pre-test and Post-test The pre-and post-test results comprised the lowest and highest scores, as well as the mean and standard deviation. It is displayed in the following table: Table 5. Descriptive Statistic on Pre-test and Post-test Test N Min. Score Max. Score Mean Standard Deviation Pre-test 30 23,33 86,67 54,78 19,05 Post-test 30 53,33 100 81,44 12,09 According to the findings of the students' pre-test and post-test, the mean pre-test score was 54.78, and the post-test score was 81.44. Furthermore, the lowest pre-test score was 23,33, the highest was 86,67, and the post-test score was 100. Finally, the standard deviation on the pre-test was 19.05, while on the post- test, it was 12.09. It shows that the students' scores improved because the mean post-test score (81,44) was higher than the pre-test score (54,78). Normality Test Before acquiring treatment, the experimental class was given a pretest. The pretest data normality test determines whether or not the pretest data follows a normal distribution. Table 5 shows the outcomes of the pretest data normality test, which was carried out using Shapiro Wilk and SPSS 23.0 for Windows. 0 5 10 15 20 25 0-49 50-59 60-69 70-79 80-100 Pre-test Post-test Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2212 Table 6. Normality Test Results for Class X RPL B SMK Negeri 4 Kendari Test of Normality (Shapiro-Wilk) Statistic Df Sig. Pre-test 0,951 30 0,180 Post-test 0,940 30 0,089 According to Table 6, the significance level for pre-test data is 0.180, which is greater than 0.05, indicating that pretest scores are regularly distributed. The significance level for post-test data is 0.089, which is larger than 0.05, indicating that post-test values are normally distributed. The pretest and post-test results are normally distributed based on their significance levels. Paired Sample Test The paired sample t-test is used to determine whether two paired samples have different means. The paired sample t-test assumes that the data follows a regular distribution. This study used the paired sample t-test to answer the question, “Does the use of YouTube videos have an effect on students' mastery and improvement of vocabulary?”. A paired sample t-test was used to evaluate the problem formulation using pre-test and post-test data. A normality test is used as a requirement to assess whether the experimental class is regularly distributed. Furthermore, hypothesis testing was carried out to determine whether treatment, namely the learning model that used YouTube videos in the experimental class, had a significant impact on student learning results. The Independent Sample T-Test test is utilized in this study, in addition to SPSS 23.0 for Windows and decision rules. Ho is accepted if the sig is more than 0.05, while Ha is rejected. The hypotheses for the study are: 𝐇𝐚: There is a significant effect of using YouTube videos on students' vocabulary mastery if the p-value < sig α = 0,05 %. This means that the alternative hypothesis (Ha) is accepted, and the null hypothesis (H0) is rejected. 𝐇𝟎: There is no significant effect of using YouTube videos on students' vocabulary mastery if p-value > sig α = 0,05%. This means that the alternative hypothesis (Ha) is rejected, and the null hypothesis (H0) is accepted. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2213 Table 7. Paired Sample Correlation Result of Pre-test and Post-test in Class X RPL B SMK Negeri 4 Kendari Paired Sample Correlation N Correlation Sig. Pre-test & Post-test 30 0,867 0,000 Table 7 indicates a significant difference in average student learning outcomes between the pre-test and post-test classes of the experimental class, with Sig. (2-tailed) of 0.000 < 0.005. The p-value < sig α = 0,05% (0,000 < 0,005) indicates the alternative hypothesis (Ha) is accepted while the null hypothesis (H0) is rejected. Independent Sample Test The following table displays the results of the hypothesis testing of pre-test and post-test data using the Independent Sample T-Test test with SPSS 23.0 for Windows. Table 8. Independents Sample T-test result of Pre-test and Post-test in Class RPL B SMK Negeri 4 Kendari Paired Differences Pre- test Post- test 95% Confidence Interval of the Difference Mean Std. Deviat ion Std. Error Mean Lower Upper T d f Sig. (2- talled) - 26,6660 0 10,467 83 1,9111 6 - 30,5747 5 - 22,7572 5 - 13,95 3 2 9 0,000 According to the result of SPSS output for hypothesis testing applied independent Sample T-Test in the table, the significance p-value (2-Tailed) = 0.000 was obtained. This implies that the result is less than the stated level of significance (0.05). The results show that the null hypothesis is rejected while the alternative hypothesis is accepted. The p-value (0,000) is smaller than the sig α = 0.05 (5%). As a result, H0 is rejected whereas Ha is accepted, meaning that watching YouTube videos improves students' comprehension skills when learning English, especially vocabulary in class X RPL B SMK Negeri 4 Kendari. Then it may be argued that students who use YouTube videos to master student vocabulary have different average learning outcomes. In conclusion, the argument presented above indicates Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2214 that the average learning results of students who use YouTube videos are 81.44, whereas those who do not use YouTube videos are 54.78. Interview The interview's aims are to explain the experience of student learning outcomes utilizing YouTube video content and to observe the difficulties or barriers that students encountered throughout the pre-test, treatment, and post- test phases of the data collection procedure. - The use of YouTube Videos can help students improve their vocabulary in learning English The initial research question examines the extent to which the incorporation of videos (YouTube) enhances students' comprehension of vocabulary in their English class. Interview data indicates that YouTube videos significantly enhance their understanding of English, particularly in terms of vocabulary acquisition. As expressed by the following students: “In my opinion, the use of videos (YouTube) in class, especially in learning vocabulary, is very interesting because this media is the first time used in class and makes me understand better when learning.” (S30, interview, 5/08/2024) “The use of YouTube videos is good because this is the first time, we have learned using video media from YouTube” (S27, interview, 5/08/2024) Another statement by S3 clarified that using videos in their class made them understand more. As expressed below: “In my opinion, this really helps me in learning English, especially in vocabulary, because we are required to focus on seeing the material in the video; even after watching, I can ask the teacher if there are words that I don't understand the meaning” (S3, interview, 5/08/2024). This shows that the learning experience using YouTube videos in English classes helps students understand the learning material. This was also clarified directly by the English teacher who taught the class through an interview, the statements are as follows: “This is unique; the first time I have taught students using videos, and based on student learning results, this media helps students learn English especially IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2215 the material displayed in the video is in accordance with the student teaching module, so this helps me more when teaching in class.” (English Teacher, interview, 6/08/2024) - The YouTube Videos make it easier for students to understand unfamiliar vocabulary The second research question examined the clarity of the vocabulary used in the videos (YouTube) and its impact on enhancing vocabulary comprehension in the English class. The interview data indicated that the vocabulary used in the YouTube videos was accessible, facilitating a better understanding of English learning for the participants. The perspectives of the following students are articulated as follows: “I think it is easy because the vocabulary in the video is easy to understand, especially before starting to watch videos from YouTube; the teacher first explains what we will learn that day. (S8, interview, 5/08/2024) Another statement by S24 also explained that the vocabulary in the video (YouTube) they watched in class was easy to understand. As expressed below: “Easy, because after watching the video when I don't understand the teacher will explain again so that I can understand the meaning of the vocabulary.” (S24, interview, 5/08/2024) This shows that the vocabulary in the video (YouTube) is easy to understand based on the interview results. This was also clarified directly by the English teacher who teaches in the class through an interview, the following statement: “The vocabulary is easy to understand because it is in accordance with the student teaching module as I said earlier, the examples given are also easy for them to understand because it is about their daily activities” (English Teacher, interview, 6/08/2024). - Benefits gained after the use of videos (YouTube) in English classes, especially in vocabulary Their experiences with using YouTube videos in their English lessons were the subject of the third study question. The results of the interviews showed that students had a better grasp of the subject after viewing the videos on YouTube. According to what the following students have said: Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2216 “After watching the video, I understand better because there are examples given in the video that are in accordance with the topic being studied.” (S25, interview, 5/08/2024) "Usually, I'm too shy to ask the teacher a question when there are words I don't understand in class, but now that we're using video content (YouTube), I chose to take a chance and ask, which improved my English test results." (S15, interview, 5/08/2024) “The advantage I get is that it makes me understand faster. usually, I need to be explained several times by the teacher before I understand; now, after watching the video, I immediately understand the meaning of the vocabulary given because in the video directly.” (S14, interview, 5/08/2024) A number of students in class X RPL C at SMK Negeri 4 Kendari reported feeling better after using YouTube videos in their lessons, which supports the idea that there are distinct advantages to using YouTube videos in the classroom. The following statements are also supported by the findings of their conversation with the English teacher: “This really helps me in class because some students immediately understand the learning without being explained repeatedly; in the past, when I explained, some students did not understand, so I needed to explain several times.” (English Teacher, interview, 6/08/2024). - The use of YouTube videos is recommended in English class Whether or whether they thought video media (YouTube) would be useful in the classroom was the subject of the fourth study question. Based on their responses to the surveys, it seems that they agree that teachers use video media (YouTube) in the classroom to help students better grasp course content. According to the opinions of these students: "I think that the usage of YouTube videos in the classroom should continue since I find that they are very helpful. In fact, I frequently utilize the YouTube videos that were provided with a video link in the class group to continue studying after school.” (S8, interview, 5/08/2024) “If possible, I use videos (YouTube) every time I learn English in class because this really helps me understand vocabulary faster, and if I don't understand, I will re-watch the video at home.” (S25, interview, 5/08/2024) IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2217 Researchers discovered that several students thought that using videos (YouTube) in their classes helped them learn English, particularly with vocabulary. This finding was based on the interview results. Talking to their English teacher also helped to put this to rest. This declares: “If only the school had more than one overhead projector, maybe this media can be used in the future not only in English classes but also in other subjects because this is very helpful, especially for me as a teacher.” (English Teacher, interview, 6/08/2024) Discussion The findings of this study confirm that the use of YouTube videos as an instructional medium significantly improves students' vocabulary mastery. This aligns with prior research conducted by Wang and Chen (2020), Hariyono (2020), and Hia (2021), who similarly highlighted the positive impact of audiovisual media on language learning, particularly in vocabulary acquisition. - Implications of YouTube Videos on Vocabulary Learning The statistical analysis of pre-test and post-test results demonstrated a significant improvement in students' vocabulary mastery. The mean post-test score (81.44) was substantially higher than the pre-test score (54.78), with a p-value of 0.000 indicating the effectiveness of the intervention. These results suggest that the integration of audiovisual materials, such as YouTube videos, caters to diverse learning styles, offering visual and auditory cues that enhance the retention of vocabulary. This is consistent with Mayer's (2001) multimedia learning theory, which posits that combining visual and verbal elements facilitates better comprehension and retention of information. Furthermore, students reported that the contextual examples provided in the videos made learning vocabulary more relatable and easier to grasp. This reflects Chun and Plass’s (1996) findings that visual aids and contextualized learning environments significantly improve vocabulary acquisition. - Student Engagement and Motivation The qualitative data obtained from interviews further underscores the motivational benefits of using YouTube videos. Students expressed enthusiasm for the innovative approach, highlighting how the videos kept them engaged and encouraged active participation in the learning process. Several students noted that they were more willing to ask questions and interact with the teacher, indicating a shift toward a more dynamic and interactive classroom environment. This aligns Andi Rachmawati Syarif, Faridawati, Nurfadilla YouTube Video in Improving Senior High Students’ Vocabulary Mastery 2218 with Huyen and Nga’s (2003) assertion that integrating enjoyable and engaging methods into language learning fosters better outcomes. - Addressing Vocabulary Challenges The study also identified that students often struggle with limited vocabulary, which hampers their ability to construct sentences and engage in communication. The use of YouTube videos addressed this challenge by providing authentic and accessible language input tailored to students’ daily lives, as highlighted by the English teacher's feedback. The repetition and reinforcement of vocabulary within the videos further facilitated retention, supporting the claims of Al-Seghayer (2005) that multimedia annotations, such as video and text, enhance learning. Limitations and Recommendations While the findings are promising, certain limitations warrant consideration. First, the study was conducted within a specific cohort of students (Class X RPL B at SMK Negeri 4 Kendari), which limits the generalizability of the results. Additionally, the focus on a single linguistic aspect—vocabulary—excludes other language skills that may benefit from similar interventions. Future research could explore the application of YouTube videos across various language competencies and diverse student populations. Moreover, expanding the range of topics and incorporating interactive YouTube content, such as quizzes or discussion prompts, could further enrich the learning experience. Addressing infrastructure challenges, such as the availability of projectors or internet access in schools, would also enhance the feasibility of implementing such multimedia-based teaching methods. Conclusion This study found that YouTube videos help students enhance vocabulary mastery. The average post-test score obtained following treatment supports this claim. Students' average outcomes after the test (81.44) exceed their mean pre-test scores (54.78). The t-test for independent samples reveals Sig. (p) (2-tailed) = 0.000 and alpha (α) = 0.05 (5%). When p < α, rejected the null hypothesis (H0) and accept the alternative hypothesis (Ha). Several limitations were identified in this study. First, the data source of this study was only taken from 30 students majoring in RPL class B of SMK Negeri 4 Kendari, so it cannot provide an understanding of students from other majors at SMK Negeri 4 Kendari. Second, all participants in this study were grade X students, so this study only focused on the knowledge possessed by grade X students about vocabulary because they were still learning English in general. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2219 Third, this study only focused on three learning topics, namely adjectives, prepositions, and action verbs, so it cannot provide an understanding of other topics in English that affect students' vocabulary mastery. This research is expected to make it easier for teachers to teach and make them more creative in using learning media, one of which is using YouTube videos, especially for students' vocabulary mastery. For students, this research is expected to provide a different and meaningful experience in learning English vocabulary through YouTube videos. For further research, it is hoped that other media can be explored to help teachers deliver English learning materials. This research has notable pedagogical implications about the substantial impact of learning media on the classroom learning process, especially in vocabulary acquisition. 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