This is from Debate Mate, a UK debate education organization.
The Format:
1. Fishbowl
This involves two concentric circles of chairs – the inner circle with
6-8 chairs and the outer with approximately 10. To start with, the inner
circle has a facilitator, some participants who support particular
positions on the topic in question and some vacant seats. Everyone else
sits as an audience in the outer circle. The facilitator introduces the
topic and a discussion begins. After a while, anyone from the audience
can come up, take one of the spare seats and join in the discussion. As
more of the outer circle move in those who have been the longest in the
inner circle are asked to move out. The format combines the coherence
of small group discussion with wider inclusiveness.
2. Consensus voting
This involves a discussion followed by all participants ranking the
various positions in preference order. The higher the preference, the
greater the number of points ie. if there are 6 participants the voter
gives his 1st preference 6 points, 2nd preference gets 5 points, and so
on. The winner is the option with the most points and the higher the
number of points the winner gets, the greater the degree of consensus.
The aim of this type of debating is that even if you strongly disagree
with someone else’s views, you have an incentive to have a proper
dialogue with them so that they rate your opinion higher in the list of
preferences.
An event would involve two consensus votes, one part-way through a
debate and the other at the end. You win if your proposal either comes
top in the final vote, or improves the most between the two votes.
Maybe this could be a format worth trying in undergraduate courses on debate and argumentation?