A simple plenary with no preparation required. Give students a few minutes to think up questions based on what they have learned – they can write these down if they like (otherwise they’re liable to forget them).
Then get one student to come up and sit in the “Hot Seat” – usually the teacher’s chair put in front of the class. The rest of the class then take turns to ask them questions – if they get the question wrong, they stay in the hot seat; if they get it right then the person who asked the question replaces them in the hotseat.
Students are only allowed to ask questions which they themselves can answer – if the person in the hot seat gets it wrong, the person who asked the question must answer it.