A whole-class structure in which the group responds to a statement by visibly taking a position — all at once, on one signal. A few participants then explain their choice, and whoever is convinced by the arguments may show it by switching position. Opinions become visible without anyone having to take the floor, and the conversation afterwards has something real to be about.
That separates it from the two things it is most often confused with. Unlike a quiz, there is no right answer: a statement with nothing left to say after choosing was a fact — and then the round turns into an oral test. And unlike a debate, winning is not the point: the return is that the group sees itself, including the voices that never sound in a class discussion.
The family goes back to the values clarification technique of the 1970s: making opinions visible without judgement. There is no single inventor — which is exactly why the game circulates in so many shapes.