The concept of a balloon debate is that a hot air balloon is coming down and in order to save any of the passengers, others will need to be thrown overboard. Different students represent the people (or objects/concepts/materials) in the balloon and argue in turn to the class (or group if being done in groups) why they should be saved. If they are thrown overboard their contribution to humanity goes with them. The audience evaluate the relative cases and vote the people off the balloon one by one. This could be done with scientists / inventors / materials / mathematical formulae / writers / artists / musicians / philosophers / public services or anything else which links to your curriculum.