Abstract :
The objecktive of this study is to determine whether there is influence of the Group Investigation (GI) towards mathematics achievement of high school students. The sample in this study is the class VIII A SMPK Sta. Maria Assumpta Kupang grade science students, consisted of 27 students. The data used in this study are taken from the result of presets and posttestof the class exsperiential with setting interactive learning Group Investigation (GI). Data were analyzed using SPSS 22.0 and manual analysis. Prior to testing a hypothesis, a prerequisite test was conducted, which is a normality check for pretest and posttest . 0,200 > 0,05 and = 0,120 < 0,254 = thus accepted and the data distributed. While the data obtained from the posttest was Asymp. Sig.( 2-tailed)= 0,110 > 0,05 and = 0,152 < 0, 294 = thus accepted and the data were normally distributed. Hypothesis testing using a paired sample test, after the data were analyzed the result was. Sig.(2?tailed) = 0,000 < 0,05 and = 20,830 > 2,056 = then is rejected. Therefore it can be concluded that there is a significant effect of Group Investigation (GI) on mathematics achievement of senior high school students. These results of this study indicate the use of question student have effect on mathematics achievement of high school students. Therefore, the authors suggest for teachers to use question student Group Investigation (GI) on learning in the classroom in accordance with the material to be taught.