The teacher provides a number of (very clear, black&white: e.g. ‘we don’t need a monarchy’, ‘pineapple on pizza is delicious’, things like that) propositions. Two students start the debate, one of them is pro, the other con. Then after some time, the teachers rings a bell (or simply announces) and they swith their point of view immediately, a 180 degrees. The one pro becomes con, and vice versa. They continue the debate in their new role. After a few minutes, two new students get a new proposition and start their debate.