🏫 Magic for the classroom: a five-minute brain break

Three tricks for the board

• The Lightning Calendar: You draw a month on a sheet of paper. In any three-by-three block, the numbers sit evenly around the middle one: whatever you take off on one side you add on the other.
• The Instant Magic Square: Somebody names any number from 30 to 99. Each row, column and diagonal holds exactly one of the four changing boxes, plus fixed numbers that add up to the rest.
• The Answer Is Always 3: You ask your friend to think of any number at all and do some sums in their head. Doubling a number and adding 6 and halving it leaves their number plus 3.

Do the first one cold, with no build-up: draw a calendar month, ask a child to ring nine dates, and answer before they've finished adding. Then challenge the class to work out how.

Making it a lesson

Let pairs try the trick on each other with their own numbers. Then ask the class to explain why it always works, in words or in algebra for older year groups. Most can get there with a hint.

The maths hiding in magic guide has every trick's topic and year group, and the grown-ups' page has the whole table.

Children performing for the class

A child who learns a trick at home can perform it for the class as a brain break of their own. It is a short, low-stakes way to speak in front of a room, with a script on the trick page and an out if it goes wrong. Ask them to keep the secret afterwards, so the next performer gets a fresh audience.

What you need, and what you don't

A board and a marker, or paper and a pencil for a smaller group. None of these tricks needs a deck of cards, coins or anything that could go missing in a classroom, and none has a step only a grown-up can do. Every one works with any numbers the class chooses, which is the point: the class tests the trick, not the teacher.

Five minutes is enough for one trick and the challenge to explain it. A whole lesson fits all three, with pairs trying them on each other in the middle and the explanations at the end.