I like to have some ideas up my sleeve for making the most of a spare few minutes at the end of a lesson. Open-ended ones work best because they can last as long as I've got. A favourite is to ask pupils to think of words that mean something different in our subject from what they mean in everyday life or in other subjects. It can be an ongoing challenge to think of them or to spot them when they crop up.
Maths ideas I've collected include: difference, product, factor, prime, negative, positive, sign, odd, even, root, index, power, rounded, interest, expression, identity, solution, term, subject, acute, obtuse, reflex, face, net, volume, plane, prism, compasses etc and, my favourite, "take-away".
Colin Foster, maths teacher, King Henry VIII School, Coventry, West Midlands