Posted in Christmas, Making totals

Christmas challenge – day 15

How many in the box?

Screenshot 2018-12-12 18.09.58.png

Digit Dog is playing a game with Calculating Cat. He has 6 tree decorations and has hidden some of them in his box. Calculating Cat has to work out how many he has hidden.

Calculating Cat is thinking about the Numicon® shape to help her work out how many are in the box.

  • She knows the whole is 6 – that’s the number of decorations Digit Dog had to start with.
  • She knows one of the parts is 3 – that’s the number of decorations not in the box.
  • Now she can work out the unknown part – that’s the number of decorations in the box – by thinking about the spaces in the Numicon® shape.

Screenshot 2018-12-12 18.18.47.png

She could have solved the problem by using number bonds. If she knows 3 + 3 = 6, she can work out the missing number.

What if………

……….Digit Dog put a different number of decorations in the box?

………..he had more decorations to start with? Fewer decorations?

Try out the game for yourself. One person hides objects in a box, their partner works out how many are hidden. Remember to explain how you work it out.

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