Mel Silberman suggests distributing index cards to your students after a lecture or a class discussion. Have each student write down a question about the material on his or her index card. Collect the cards, shuffle them, and redistribute them to the students. Now ask the students to read their cards and think of answers to their questions. If you have enough time, you can go around the room and have every student give an answer. Otherwise, ask for volunteers or call on students to read their questions aloud and give answers. -DG
Source: Mel Silberman. "Everyone is a Teacher Here." 101 Ways to Make Training Active. Johannesburg: Pfeiffer & Company, 1995. 174-75