The aim of the research was to find out the effectiveness of authentic material
for teaching vocabulary. This research used quasi experimental method in which the
sample was based on the school policy. Two classes were chosen eight D as control
class and eight E as experimental class. Pre-test and post-test were used to find the
data. The test was in multiple choice forms consisting 20 items for each test. T-test
formula was used to find the data. The result of the research showed that there was a
significant difference of the students’ in mastering vocabulary between the students
who were taught using authentic material and those who were taught using text boox.
It could be seen on the result of computation of t-test, where t-result is 3.478 and ttable
1.674 at the significant level α=0.05 in df=54. The result was higher than t-table
(3.478>1.674). It means that the hypothesis that authentic material was effective for
teaching vocabulary was accepted.