Abstract :
The objective of this research to indenify the difficulties faced by the seventh grade
dtusentd at MTs Darul Ilmi Batang Kuis, to identify factors of causing the students
difficulties in memorizing the vocabulary at the elevent grade students at MTs Darul
Ilmi Batang Kuis in academic year 2020/2021. This research is quantitative research.
The subject of the research was the eleventh garde of MTs Darul Ilmi Batang Kuis in
academic year 2020/2021. The total of the population was 25 students and the
researcher took each experimental and controll class are 25 students of the sample. In
collecting the data the researcher used test in the form of multiple choices as the
instrument. The tests were Pre-test which was given before the treatment and the Post-
test which was given after the treatment. Then, the data obtained were analysed by using
t-test in SPSS IBM 16 with 5% (0.05) significance level. Further, the reseracher found
that the mean score of post-test in test result also presents that to (8.984) was higher
than the t-table the significance level 5% (0.05) with the degree of freedom 23 is 1.699.
Therefore, the t0 result > t-table generated that H0 (null hyphothesis) was rejected and
Ha (alternative hyphothesis) was accepted. The calculation of the effect size was 1.37
which the range of the effect criteria included to strong effect. Thus, Duolinggo
Application has significant effect on the students? vocabulary mastery at the sevent
grade of MTs Darul Ilmi Batang Kuis.