Here is one idea that takes no preparation and can keep your students talking for a long time. I'm borrowing from de Bono's Lateral Thinking. De Bono, in one of his books, spoke of the importance of trying to see situations from various perspectives. Also I'm taking some ideas from Willis and Willis' Task Based Learning and Nation's Just Say It:
Tell the students story where there can be different viewpoints. For example, there was a story in a newspaper about an eagle that escaped from its cage in a zoo and was difficult to capture. It was perched on a high branch and is resisting the efforts of the keepers to lure it back to its cage.
Divide the students up into four equal groups. Ask each group to imagine a different viewpoint in the situation. One group should imagine and discuss the viewpoint of the keeper, another group should consider the viewpoint of a newspaperman, a third group should consider the eagle and another group a passerby.
The groups should discuss each viewpoint and from that viewpoint how they would describe their feelings and attitudes in that situation.
After they get started, check on them and make sure they are getting some ideas. You can further seed their discussion with these ideas:
The keeper's point of view: the bird may fly away and get lost or shot unless it is coaxed back soon. It is uncomfortable having to climb up trees after the bird and one feels a bit foolish. Someone is to blame having let it escape.
The newspaperman's point of view: the longer the bird stays out the better the story. Can one get close enough to get a good picture? One ought to find some other interest such as different people's ideas on how to catch the bird.
The eagle's point of view: wondering what all the fuss is about. Strange feeling not to be in a cage. Getting rather hungry. Not sure in which direction to fly.
The onlooker's point of view: hoping the eagle will fly away and be free for evermore. Amused to see the strenuous efforts being made to catch the bird. The eagle looks so much better out on its own than inside a cage. Maybe one could show how clever one was by catching the bird when no one else could.
Each group of students could develop what they would say to represent their viewpoint. After some time the teacher would take one student from each group to form new groups. Then each person would discuss their viewpoint in their new groups.
Afterward you can have a general discussion of the situation and talk about any interesting things that the students contributed to the talk.