This study aims to evaluate the impact of the group
discussion learning approach on improving students' critical
thinking skills in writing essays for Indonesian language
subjects at SMP Negeri 1 Tempurejo. This study uses a
quantitative approach with a pretest-posttest design with a
non-equivalent control group. The participants consisted of
two classes: IX B as the control group and IX D as the
experimental group, each containing 20 students. Data were
collected using essay writing assessments and direct
observation to evaluate student engagement during
classroom learning, after which they were evaluated using a
paired sample t-test. The results showed an increase in the
average score of the experimental class from 77.5 to 91.3 (an
increase of 13.8 points), while the control class increased
from 56.8 to 66.9 (an increase of 10.1 points), indicating a
significant difference between the two classes. The
experimental class experienced a percentage increase of
17.81%, indicating a relative effectiveness that was 36.63%
superior to the standard learning method. As a result, the
group discussion method significantly improved students'
critical thinking skills in essay writing.