The cooperative learning method, Jigsaw II, was implemented in a grade four social studies class for the purpose of examining the verbal interactions among students as they learned from each other. Jigsaw II is structured to enhance cooperation because each student has exclusive information that is needed by other group members to do well on a test. It was hypothesized that the more capable students in a heterogeneous learning group would help the less capable ones learn the material. As the lower ability students gained proficiency in teaching their information, the variance in the rates of speaking would be less at the end of the implementation of Jigsaw II than at the beginning. This did not happen. There was homogeneity of variance between the rates of speaking at the beginning and the end. The rate of positive verbalizations (learning the information and group functioning) was over 80% at the beginning and increased slightly during the implementation of Jigsaw II, but was not statistically significant. There was large variability in the rates of verbalizations among students, as well as large variability in rates of speaking for individuals across different learning group sessions. Any trends in changes of rates of speaking were obscured by the high variability. The verbalization rate of the high ability students doubled, the rate of the middle ability increased 32% and the rate of low ability students remained unchanged. On five quizzes administered over the learning unit, the high ability student attained the highest quiz scores, but the low ability students performed as well as the middle ability students.