This is a technique for a large number of people (max I've done successfully is 50) to have a good discussion.

Put five (or so) chairs in a circle in the middle of the room, and all the rest concentrically around it.
	*One of the chairs must remain empty.
	*Only someone in one of the chairs may speak.
	*Anyone may sit down in the empty chair.
You will need some light facilitation if people don't get the rules immediately.
You MUST have a good topic, otherwise people just come into the circle to air their views, not to take part in a discussion. This means a topic where there are clear conflicting views.
About an hour is usually enough.

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See FishBowl, ParkBenchPanel