Divide your class in half. One half will form the center circle, facing inward. The other half of the class will form the outer circle, facing inward as well.
The students in the inner circle will discuss a predetermined topic.
The outside circle will be listening to the discussion, making note of interesting, new, or contradictory information. They are not allowed to say a word at this point.
The inner and outer circles can then switch positions and repeat the steps above.