Posted in Christmas, WODB

Christmas challenge – day 12

Which one doesn’t belong?

Digit Dog and Calculating Cat were decorating their Christmas tree when they thought they’d make up a Which one doesn’t belong? question.


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What do you think?

It doesn’t matter which you choose as long as you can give a reason for your choice.

Look at each Santa in turn and think of a reason why it doesn’t belong.

How many different reasons can you think of?

Make up your own Which one doesn’t belong?

Now ask “What is the same about all the Santas?” “What is different?

Check out this post.


Posted in WODB

Digit Dog is making his own “Which one doesn’t belong?”


What do you notice?

Do you agree with Calculating Cat? What does she mean by “a double”?

Can you think of reasons why each of the pairs of dice could not belong?

Choose each pair of dice in turn and think of reasons why it doesn’t belong. Can you think of more than one reason?

Put this picture on your challenge board and come back to it during the day. How many answers can you think of by the end of the day?

Can you make up a “which one doesn’t belong?” of your own?

Posted in Books, Shape, WODB

which one doesn’t belong? A Shapes Book by Christopher Danielson

Really enjoying this book:


A great way to focus on the properties of shape and to start conversations and thinking. Each page has four shapes and the challenge is to find which one doesn’t belong. Any answer is acceptable as long as it is true. The important thing is to have a reason for your answer.

Can you find a reason why each of the shapes on the cover don’t belong?

How is the shape you have chosen different from the others?

What do you notice?

By doing this activity you are encouraging learners to notice similarities and differences, to use correct mathematical language, to reason and to explain their thinking.

The question on each page of the book “Which one doesn’t belong?” is the same but some pages are more challenging than others. They really make you think.

Find more ideas from this author at


Posted in WODB

Which one doesn’t belong?

Look carefully at the pairs of bugs and decide which pair doesn’t belong. Explain your thinking. Explain your reasoning.

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Take each pair in turn and give a reason for why it doesn’t belong.

How many different reasons can you find?

Make up your own WODB.