Abstract :
The objective of this study is to find out whether or not there is significant
effect of English Vocabulary application on the students? vocabulary mastery at the
eighth grade of MTs Hifzhil Qur?an Medan. This research is a quantitative research
with quasi-experimental design. It was carried out in the eighth grade of MTs
Hifzhil Qur?an Medan under academic year 2019/2020. The total number of
population was 235 students and the researcher took 25 students for experimental
class and 25 students for controlled class which means 50 students as total of the
sample. In collecting the data, the researcher used tests in the form of multiple
choices as the instrument. The tests were pre-test which was given before the
treatment and post-test which was given after the treatment. Then, the data obtained
were analyzed by using t-test in SPSS V.25 with 5% (0.05) significance level.
Further, the researcher found that the mean score of post-test in experimental class
was higher than controlled class (79.60 > 72.20). The t-test result also presents that
t0 (2.422) was higher than the ttable in the significance level 5% (0.05) with the
degree of freedom 50 is 2.00856. Therefore, the t0 > ttable generated that H0 (null
hypothesis) was rejected and Ha (alternative hypothesis) was accepted. The
calculation of the effect size was 0.78 which in the range of effect criteria included
to moderate effect. Thus, English Vocabulary application has significant effect on
the students? vocabulary mastery at the eighth grade of MTs Hifzhil Qur?an Medan.