I use TurningPoint NXT clickers to get the Immediate Feedback Assessment Technique. The projector displays a grid. As teams answer they get a green check mark or red "x". They can go back and change their answer until they get it right. The software records and maintains each response. When they finish, I get the report of how many tries they had for each item. I grade accordingly. Students love it and they do the cheering and hi-five thing as they go through.