Posted in Calculating, Christmas, Number sense, Numicon

Christmas Challenge – Day 2

Two Numicon® shapes – which shapes are in the Christmas sack?

Screenshot 2018-11-30 18.20.20

Show me 2 shapes that could be in the sack. Why do you think that? Are you sure? Convince me.

Are they the only 2 shapes it could be?

How many pairs could it be?

If I show you one of the shapes will you know for sure what the other one is?

Encourage children to explain their reasoning. At first, why don’t they know for sure which two shapes are in the sack? How many possible pairs can it be? Show one pair, and another, and another………..

When you know one shape, how can you be sure what the other shape is?


  1. Put one shape in the sack and give children clues so that they can work out which shape it is. An opportunity to model mathematical language.  My shape is:
    • one more / one less than………
    • two more/ two less than………
    • in between……
    • an odd/even number
    • If I add …and …..I get this number
    • If I take my number away from 10, I am left with……
    • The difference between my number and 6 is………
    • ……more than……
    • a multiple of ……….
    • a factor of………Get the children to ask questions about your shape to work out which one it is.
  2. Put 3 shapes in the sack. The total is 15 which shapes could they be? What if I show you 1 shape, how does that change your thinking?
  3. Vary the totals, vary the number of shapes.






3 thoughts on “Christmas Challenge – Day 2

  1. Hi
    Just wondering if there’s a particular year group you’d use these with. I teach year 2. Also how would you recommend to show differentiation in their books
    The resources look brilliant and am really keen to use them
    Many Thanks


    1. The differentiation is in the questioning and the reasoning. So if children need to practise number bonds to 10 – use challenge 2 as it is – can they reason that it could be any of the bonds to 10? Can they explain how they know? Can they convince you that they have found all possibilities? Can they explain why they can’t be sure which two shapes they are without having more information? So what happens when I show 1 of the shapes? Why can you now work out the other one? If chldren can do this then do 3 shapes and ask the same questions – investigate different totals – how many possible combinations could it be if the total was 23 and there were 3 shapes? What’s the highest total it could be? Lowest? Why? Show your thinking. Ask children to make up their own problem for their friends. It’s not about getting the answer but explaining your reasoning. It’s a flexible challenge and can be used across year groups and abilities – it depends on the questions you ask. Hope this helps.


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