This book, first published in 2012, has been a hugely popular one on INSET days. It’s a perfect way of ensuring that all the children are engaged, and that everyone’s ideas are heard.
Simply put, give the children a set of photocopiable cards, each of which has a mathematical statement. Ask the children to sort them into three groups depending on whether they think the statement is always, sometimes or never true. The whole group must agree before moving on.
If you’ve ever tried this activity, you know how powerful it is at developing reasoning skills and communication skills. Highly recommended.