The research on CL has a validity and generalizability rarely found in the education literature. A wide variety of tasks, ways of structuring cooperation, and measures of the dependent variables have been used. Subjects have varied as to age sex, economic class, nationality, and cultural background. Demonstration studies have been conducted in real classrooms over extended periods of time. The research has been conducted by scholars with markedly different orientations, working in different settings and countries, over a period of nine decades.
CL affects many different instructional outcomes simultaneously.
As already noted, these include achievement, positive relationships among students, and psychological health. CL is, therefore, a very cost-effective instructional procedure. Quite a bit is known about the essential components that make it work. Placing students in groups and telling them to work together does not in and of itself result in cooperation. Instructors must carefully structure positive interdependence to ensure that all students are committed to each other as persons and to each other's success.