Received in revised form

In this study, we analyzed verbal interactions among 32 students in 7th graders ’ science cooperative learning at the levels of turns, interaction units, and conflict behavior units, and compared their verbal interaction patterns between the heterogeneous and homogeneous groups by students ’ collectivism. The relationships of verbal interactions with the achievement test scores and the increase of the achievement test scores were also investigated. In the analyses of turns, the distributions of the subcategories of the statements related to the task were found to be similar in both groups, and the frequency of ‘explain’ was highest. The frequencies of interaction units were higher in the homogeneous groups than the heterogeneous groups, and the frequency of ‘symmetric interaction ’ was highest. In the heterogeneous groups, the frequencies of turns and interaction units for the students of high collectivism were higher than those of low collectivism. The frequencies of conflict behavior units were generally low, but the rates were similar in both groups. In the case of the homogeneous groups, the frequencies of ‘avoiding’ and ‘competing ’ for the students of low collectivism were high, and the frequency of ‘cooperating ’ for the students of high collectivism was high. In addition, the qualitative differences between the two groups were found in the interaction units and conflict behavior units. The achievement test scores and the increase of the achievement test scores were positively related with the sum of the frequencies of th