Sit children in two concentric circles, an inside ring and an outside ring, so that everyone is facing a partner. Give them something to talk about.
For example, "share everything you know about triangles". After two minutes the children on the outer circle move anti-clockwise until you say stop.
Now everyone should be facing a new partner, talk starts again and conversations can build on what went before.
You can stand back and assess what children know and plan the next steps in learning based on their discussions. Keep the wheels in motion for as long as you need to, then share ideas as a class.
Why not give this merry-go-round strategy a whirl? It works well for any number of topics and it is a great way of getting to know maths inside out John Dabell is a numeracy consultant and teacher trainer