MELINDA KRISENDIA WEO Pengarang SANTRI EMILIN PINGSABOI DJAHIMO Dosen Pembimbing 1 GRACIA M. N. OTTA Dosen Pembimbing 2 Santri Emilin Pingsaboi Djahimo Ketua Penguji Marcelinus Yeri Fernandez Akoli Penguji 2 Gracia M. N. Otta Penguji 1

This thesis is entitled “INCREASING VOCABULARY BY USING AUDIO-VISUAL MEDIA THROUGH WATCHING ENGLISH SUBTITLED VIDEOS ON “TEDED” YOUTUBE CHANNEL (A CASE STUDY OF THE SECOND-GRADERS STUDENTS IN SMA NEGERI 1 KOTA KUPANG).” This research aimed at knowing the improvements in students' vocabulary after watching the videos from the TED-Ed YouTube channel and knowing students' perceptions after watching the videos from the TED-Ed YouTube channel. This research aimed to answer the following research questions in this study which are: (1) Can the implementation of using videos on the TEDEd YouTube channel increase the vocabulary of the second-grade students in SMA Negeri 1 Kupang (2) What are the students’ perceptions toward the implementation of using audio-visual media through watching videos on the TEDEd YouTube channel in increasing their vocabulary? The writer conducted this research in SMA Negeri 1 Kota Kupang and this research used mix-method to get both qualitative and quantitative data. The sample in this research was one class of second-grade students with a total sample of 25 students, as long as the writer implied one group pretest-posttest design. In collecting the data, the writer used the modified version of VKS (Vocabulary Knowledge Scale) as the pretest and post-test and to know students' perceptions the writer implied questionnaires and interview. The results of this research showed: (1) The score of the post-test was higher than the score of the post-test. The mean score of the pre-test is 77 and the mean score of the post-test is 129.4, the result showed that the difference between the pre-test and post-test mean is 52.4, which means the treatment impacted increasing students' vocabulary. (2) The results of the questionnaires and interview showed that most of the students enjoyed learning vocabulary by using audio-visual media by watching English-subtitled videos on the TEDEd YouTube channel. The questionnaires’ results showed the total percentage of the students who answered yes to each question was more than 80% and the results from the interview complimented the data from the questionnaires which implies that the use of audio-visual media through watching English-subtitled videos on the TEDEd YouTube channel increased their vocabulary. In conclusion, the results of the pre-test and post-test, also the results of the questionnaires clearly showed that the use of audio-visual media through watching English-subtitled videos on the TEDEd YouTube channel increased students’ vocabulary. Keywords: vocabulary, media, audio-visual, increasing, videos, vocabulary knowledge scale.