Penelitian ini bertujuan untuk mengetahui apakah penggunaan WordUp mobile aplikasi berpengaruh terhadap peningkatan kosa kata bahasa Inggris siswa serta untuk mengetahui persepsi siswa tentang aplikasi WordUp. Pendekatan kuantitatif dengan metode kuasi experimental digunakan dalam penelitian ini. Sample terdiri dari dua kelas yaitu experimental group (VIII Index 2) yang terdiri dari 18 siswa dan control group (VIII Index 1) sebanyak 18 siswa. Siswa kelas experimental belajar menggunakan aplikasi WordUp sedangankan kelas control belajar menggunakan metode konvensional. Test dan kuesioner digunakan sebagai intrumen untuk penelitian ini. Hasil analisis data menunjukan nilai rata-rata pada kelas experiment untuk post-test (71.56) lebih tinggi dibanding nilai rata-rata pretest (42.78). Berdasarkan nilai T-test diketahui Sig. (2-failed) adalah 0.000 lebih rendah dibanding level signifikan (0.05). Dapat disimpukan bahwa, hipotestis nol (H0) ditolak sedangkan hipotesis alternatif (H1) di terima. Untuk kuesioner menunjukan hasil persepsi positive terhadap penggunaan aplikasi WordUp dalam pembelajaran kosa kata bahasa Inggris.
This study aims to determine whether the use of the WordUp mobile application has an influence on enhancement of students' English vocabulary and to find out students' perceptions of the WordUp mobile application. A quantitative design with a quasi-experimental method was used in this research. The sample divided into two classes, namely the experimental group (VIII Index 2) which consists of 18 students and the control group (VIII Index 1) consists of 18 students as well. The experimental class students learned using the WordUp mobile application, while the control class learned using conventional method. Tests and questionnaires were used as instruments for this research. The results of the data analysis revealed that the mean score in the experimental class for the post-test (71.56) was greater than the mean score for the pre-test (42.78). Based on the T-test result, the Sig. (2-tailed) was 0.000, which was less than the significance level (0.05). It can be concluded that the null hypothesis (H0) was rejected while the alternative hypothesis (H1) was accepted. For the questionnaire, the results indicated a positive perception of the use of the WordUp mobile application in English vocabulary learning.