Related number stories

Keep the whole in view

Five red counters and three blue counters make eight counters altogether. The whole is eight. The parts are five and three.

The parts can change order:

Both facts describe the same whole. Swapping the parts does not make a different total.

Now hide the three blue counters. Five remain. Put them back and hide the five red counters. Three remain:

Addition puts the two parts together. Subtraction starts with the whole and finds a part. These are related facts.

Try the model. You can change your answer or look at the worked model. This activity has no score.

Check the amounts and how they fit together. Moving a counter inside a box does not change its value. You can also draw on paper and compare with the public answer.

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First part: 5 counters. Reference whole: 1 counters. Bars use the same scale.

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Second part: 3 counters. Reference whole: 1 counters. Bars use the same scale.

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Make a new split of eight. Say the two addition facts and the two subtraction facts. If both parts are four, some facts will look the same.

The words help you choose a fact

A box held seven toy cars. Two cars are on the floor and the rest are still in the box. How many are in the box?

Seven is the whole. Two is a part. The missing number is the other part. So 7-2 = 5. Check with 2 + 5 = 7.

“The rest” does not always tell you to subtract the two numbers you see. First find the whole and the two parts.

Check your understanding 1 The whole is missing

Some ducks are on a pond. Three fly away and six stay. How many ducks were there at the start?

Number of ducks at the start

Check answer

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Nine ducks: 3 + 6 = 9. The subtraction fact 9-3 = 6 tells the story backwards. 6-3 would remove ducks from the group that already stayed.

Ten ones make one ten

Counting every object can take a long time. A group of ten ones can be called one ten. It is still ten objects.

Try the model. You can change your answer or look at the worked model. This activity has no score.

Check the amounts and how they fit together. Moving a counter inside a box does not change its value. You can also draw on paper and compare with the public answer.

Show solution

The same quantity: 10 counters. Reference whole: 1 counters. Bars use the same scale.

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Use the exchange to change one ten into ten ones. Undo it to change the ten ones back. The way you show the amount changes; the amount stays ten.

For 9 + 4, use one of the four to make ten with nine. Three remain. So 9 + 4 = 10 + 3 = 13. Check the four you added: one and three still make four.

Check your understanding 2 Make ten, then add the rest

Find 8 + 5. How many of the five make ten with eight? What is the total?

Say or write how you split the five

Eight plus five

Check answer

Show answer

Two of the five make ten with eight. Three remain, so 8 + 5 = 10 + 3 = 13. Compare your explanation yourself; the number check only checks the total.

Before you move on

Make your own story with a whole of twelve and a part of five. Find the other part. Check it with addition. Try without counters first; use them if they help you explain.