# Domino Sorting

## Problem

*Domino Sorting printable sheet*

Here are some dominoes taken out of the full set:

## Getting Started

Have you added up or counted the spots on each domino?

Can you think of some pairs of numbers that add to five?

## Student Solutions

Natasha and Izzy from Finney Primary School say:

Our solution was that we gave each domino a number going left to right (and top to bottom) . The first domino 1, second 2 and so on. The first solution was the odd numbers (in order 1, 2 so on) were:

So, in other words the dominoes which have an odd number of spots are:

And the rest have an even number of spots. Natasha and Izzy say that none of the dominoes was left over. Rachel from Brynteg School explains that:

All whole numbers are even or odd. The numbers on the dominoes are even or odd so there are no numbers left.

Jack and Peter answered the second part of the problem. They wrote:

Well done, Jack and Peter. There are other ways to make pairs which total 5 and Thomas from Reading explains why:

## Teachers' Resources

**Why do this problem?**

This problem will help learners to become more familiar with odd and even numbers, and number bonds to five. It will also challenge them to justify findings.

### Possible approach

If you have an interactive whiteboard, you may find our Dominoes Environment useful for this problem.

- How can you sort them?
- Can you make a pattern?
- Can you make a snake?
- What did you notice?

### Key questions

### Possible extension

You might want some children to find all the different ways of making pairs that add to $5$. This could be by picking two and then replacing them, or by finding all the different combinations which could be made at the same time (the problem as written focuses on the latter). Whichever way, part of their task should be to convince you that they have not missed any pairs out.

Domino Join Up is a similar problem which gives practice in number bonds to six, and could be used as an extension to this problem.

### Possible support

Children would really benefit from having sets of dominoes to manipulate as this allows them to change their mind easily, so giving them more confidence to begin the task, and also prevents them from using any domino twice.