The statistical test used to make a comparison of cooperative learning effects on mathematics achievement between experimental group students in Boys’ and Girls’ schools was also the independent-sample t-test. The Girls’ school scored mean of 47.75 (SD = 2.55), which is slightly higher than the Boys’ school with mean score of 47.37 (SD = 2.97). As mentioned in Table 4, a non-significant result was found t (38) = -0.42, p > 0.05, which indicated that there is no statistically significant difference in mathematics achievement post-test mean scores between experimental group students in Boys’ and Girls’ schools. The results show that experimental group students in Boys’ and Girls’ schools were equal in their performance in mathematics achievement after cooperative learning implementation.