On mini-white boards or post its, pupils have 1 minute on their own to write down two things learnt (last lesson or this lesson). Then in pairs, they have 1 minute to make it 4 things. Then two pairs combine and have to make it 8 things. This could also be used to generate ideas regarding new topics.
This strategy can also be effective at promoting verbal feedback. Pose a question with a goal and time frame for pupils to discuss. Listen carefully and circulate to all responses. Select pupils to feedback, then others to contribute further.