SANI KARLIN TALLAAN Pengarang ELISNA HUAN Dosen Pembimbing 2 Alexander Home Kabelen Dosen Pembimbing 1 Alexander Home Kabelen Ketua Penguji Elisna Huan, S. Pd., M.Hum Ketua Penguji Marcelinus Akoli, S.Pd., M.Ling Penguji 2

This thesis is entitled “A study of using mind mapping to develop english vocabulary skill of ninth grade students of smpnegeri 1 amanubanbarat in the academic year 2022/2023”. The problem of this study is how effective is mind mapping to develop English vocabulary skill of ninth grade students of SMP Negeri 1 Amanuban Barat in the academic year 2022/2023? This study aims at knowing how effective mind mapping to develop English vocabulary skill of ninth grade students of SMP Negeri 1 Amanuban Barat in the academic year 2022/2023. The method used in this research was quasi experiment with quantitative approach. The subjects used were 89 ninth grade students of SMP Negeri 1 Amanuban Barat in the academic year 2022/2023. The data were collected by using posttest. The questions of test were designed using Cronbach’s (2004) theory. The result proves that mind mapping affect the development of students’ English vocabulary skill. The mean score for the experimental group that used mind mapping is 89.67, while the control group is 63.91 with t-count 8.801 for α= 0.05. The percentage of mind mapping effectiveness is 40%. The result of data analysis shows that the use of mind mapping has average level to teach English vocabulary. Finally, based on the result of the data analysis, the writer offers a suggestion that teacher has to find out the appropriate and inovative teaching method in delivering a topic in this case, using mind mapping in teaching English vocabulary is highly recommended. Keywords: Study, Mind mapping, Develop, English vocabulary.