I was lucky enough to have great cooperation in my group work projects. There was one group project, where there was 7 of us and one of us did not do his part. We emailed the the instructor who contacted him and warned him of his grade. He didnt want to participate so we were allowed to leave him off our project and he had to do it on his own. I have found that a quick email to the instructors normally takes care of people who wont participate. So its not like University of Phoenix, where if someone doesnt participate its ok.
I have had groups as small as 3 people and as large as 7. It depends on the instructor and how they divide you up. All in all, GCU is a great place to attend and I havent had any problems there, I am currently a student there once again, I am taking some math courses that will help me obtain a certification in math and the courses will help me with my analysis when doing my dissertation for the doctorate I hope to start in the Fall.