Edutopia cites use of the Collaborative Learning model—which is much like cooperative learning—as a key factor in students’ achievement in Oakland CA’s College Prep program’s advanced placement (AP) exams. Their percentage of students taking AP exams was 40% vs a national average of 23% (USA); perhaps more significantly, 37% more students passed the exams than the national average. It’s just one study, but it’s worth a look.