The year 3s were delighted when they trooped into their classroom for what should have been an ordinary maths lesson. Instead, there was evidence that a party had taken place overnight. Not just any party, but one held by magical people, some of whom appeared to have been the size of fairies, while others seemed to have had "giant" status.
On the floor were items that had been hastily discarded in the magical guests' rush to leave. And there was a letter from Chief Inspector Twinkletoes of the local police, which read: "We have reason to believe that last night a magical party took place in your classroom. We need your help to apprehend the suspects. On your tables is evidence to help you create a life-size image of the magical people."
The children paired up (care was taken to mix up the range of abilities) before forming groups of six. In front of them was carefully wrapped "evidence". One group had some tiny shoes, another a pair of flippers from a doll, a third a photocopy of an enlarged thumbprint, a fourth some large clogs, and on the final table was a huge handprint.
The children spent time thinking about how they could work out the sizes of the magical people before most groups created their own non-standard unit to use as a measure. One group realised they could measure the dimensions of their own bodies, then use the small shoe to work out how long the legs and arms of their magical person should be. (The leg, for example, turned out to be three shoes long.) The group working with the thumbprint calculated that it was four times as long as their own thumbprint and worked out the dimensions of their giant by multiplying their own limb dimensions by four.
At the end, each group described how it had calculated the dimensions. This evidence was forwarded to Chief Inspector Twinkletoes to help him apprehend these unusual suspects.
The children adored the lesson and we were impressed by their emerging understanding of ratio and proportion. We followed it up with a cookery session in which they baked for their magical person. As far as we know, the culprits are still at large.
Tony Cotton is the author of Understanding and Teaching Primary Mathematics. This class was carried out by Emma Dobson at St Mary's Catholic Primary in Horsforth, Leeds
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