It is important to focus the student evaluation on the process of the group as opposed to the product. The expectation that one will have to summarize, explain and teach what one is learning impacts one's learning strategies. Higher level strategies are used. The discussion within cooperative learning situations promotes more frequent oral summarizing, explaining, and elaborating of what one knows. This oral rehearsal consolidates and strengthens what is known and even serves to organize the concepts.
Heterogeneous groups stimulate divergent and creative thinking.
Students with incomplete information interact with others who have different perspectives and facts. This promotes greater perspective-taking ability. Ideas are externalized and critically examined. This enhances learning. Feedback concerning the quality and relevance of contributions improves one's reasoning or performance.