Pengaruh Penggunaan Aplikasi Duolingo Untuk Mengembangkan Kosakata Bahasa Inggris Siswa Kelas Sepuluh SMA Negeri 1 Pamona Selatan

The objective of the research is to find out the effectiveness of using Duolingo application in students’ vocabulary in the tenth grade of SMA Negeri 1 Pamona Selatan. This research used Quasi-experimental research design. In selecting the sample, the researcher applied cluster random sampling technique. The research sample was class X A as an experimental group and class X B as a control group. The data was collected by using pre-test and post-te st. The result of data analysis shows that there is a significant difference between the result of pre-test and post-test of both groups. The mean score of experimental group was 85.29 from 57.64 in pre-test and the control group was 70.44 from 54.71 in pre-test. By applying 0.05 level significance and degree of freedom (df), it can be seen that the value of t-counted was (5.409) is higher than t-table (1.667), which means the hypothesis is accepted. Referring to the result, it can be concluded that using Duolingo application has a significant effect on the development English vocabulary of the tenth grade students of SMA Negeri 1 Pamona Selatan.
Keywords: Vocabulary, Duolingo Application, Effectiveness.