The purpose of this research was to find out the effectiveness of
Improvisational Exercise technique in teaching English vocabulary. This research
used quasi experimental research and the subjects were 60 students which was
divided into two groups/classes, namely control class and experimental class. The
experimental class (VIIIB) was treated using improvisational exercise technique and
the control class (VIIIA) was not. The teaching materials of this research were
recount and narrative text. The instrument of collecting the data was test. There were
two tests, pre-test was given before the treatment and post-test was given after the
treatment. The result of t-test analysis showed that it was higher than t-table value
with degree of freedom (df) 58 at level significance 0.05 (3.5179 > 1.6715). Besides
that, the the mean score of experimental class in the post-test was higher than control
class (76.22 > 69.11). Based on the study result, the study showed that
improvisational exercise was effective for teaching vocabulary, especially in
meaning aspect, word classes and word use aspect.