An organising technique and resource for discussion. Good for revision, for practising retrieval and for deepening thinking. (Good for all ages, too.)
Using sharp scissors, cut up some mini-whiteboards to make a set of unique, four-piece jigsaws, like this. (This is surprisingly quick and easy to do, and oddly satisfying.)
You now have a robust, re-usable resource.
On each jigsaw, use a board pen to write four connected things which you want pupils to think about. These might be terms, facts, quotations, diagrams, concepts or any other fragments of knowledge. Each jigsaw should have a different theme or connecting principle. Like this.