This study aims to determine the effect of Group Investigation type cooperative
learning on mathematical problem solving abilities and confidence of class VII
students of Rembang 2 State Junior High School 2017/2018 school year. The
population in this study were seventh grade students of Rembang 2 State Junior
High School 2017/2018 school year. the sample in this study is class VII E as the
Experiment class and VII C as the Control class which is taken by Cluster
Random Sampling technique. The instrument used in this study is Post test. Post test results were obtained after students in the experimental class followed Group
Investigation cooperative learning and the control class followed direct learning.
Post test results were processed using IBM SPSS Statistic 21 Software by
performing the Mann Whitney test for post test results and Independent t Test tests
on questionnaire results. The sig value obtained on the Mann Whitney test for post
test results is 0.0355 and the sig value on the Independent t Test test for the results
of the questionnaire is 0.0075. So it can be concluded that students' mathematical
problem solving and self-confidence abilities that follow Group Investigation type
cooperative learning are better than mathematical problem solving abilities and
confidence by using direct learning.