A good exercise at the end of a class/course/seminar, is to divide the class into 2 teams. Have them physically group together at opposite sides of the classroom. Ask 10 questions on the major content items of the course. Keep track on which group correctly calls out the answers to the most questions first. Be prepare to have a tie-breaker. Could use an independent judge to determine who was right/wrong. Offer a prize of some kind (the undying gratitude of the instructor, or some such).