I am a high school math teacher. Last year I experiemented with cooperative learning, and was very pleased with the results. As I continue to read on the topic the concept of "positive interdependence" is frequently indicated as a significant attribute. Some authors believe it is the most important attribute. I find little information on how to create this atmosphere. I would be interested in hearing what strategies you have tried in this area, and how/when were they effective, or conversely, not effective. Thanks in advance.