Number Bonds Explained: What They Are and Why They Matter

Your child comes home talking about "number bonds" and you nod along pretending you know what that means. We've all been there.

Number bonds are one of the most important building blocks in KS1 maths. Once you understand them, you'll see why teachers spend so much time on them — and how easy they are to practise at home.

What are number bonds?

A number bond is simply a pair of numbers that add together to make a specific total.

For example, the number bonds to 10 are:

• 0 + 10
• 1 + 9
• 2 + 8
• 3 + 7
• 4 + 6
• 5 + 5

That's it. Nothing complicated. It's knowing which pairs of numbers combine to make a given total.

In Year 1, children focus on number bonds to 10 and to 20. In Year 2, they extend this and use number bonds to support more complex addition and subtraction.

Why do they matter so much?

Number bonds are the foundation for mental arithmetic. When a child knows — instantly, without counting on fingers — that 7 + 3 = 10, everything else becomes easier.

• Addition: If you know 6 + 4 = 10, then 16 + 4 = 20 is obvious.
• Subtraction: If you know 8 + 2 = 10, then 10 - 8 = 2 comes automatically.
• Problem-solving: "I have 10p. I spend 6p. How much is left?" becomes instant.

Think of number bonds as the multiplication tables of addition. The goal is automaticity — knowing them so well that no thinking is required.

How schools teach them

Teachers use lots of different representations:

• Part-whole models: A circle (the whole number) connected to two smaller circles (the parts)
• Ten frames: A 2x5 grid where children place counters
• Bar models: A rectangle split into two parts
• Number stories: "There are 10 apples. 4 are red and the rest are green. How many are green?"
• Concrete objects: Cubes, counters, fingers

The key is that children see number bonds in many different forms, so they build a deep understanding rather than just memorising.

How to practise at home

Make it physical

Use real objects. "We have 10 grapes. If I eat 3, how many do you get?" Fingers are great too — hold up 10 fingers, fold some down, count what's left.

Play games

• Snap: Make cards with number bonds pairs. 7 and 3 are a match. 6 and 4 are a match.
• Bowling: Set up 10 "pins" (plastic cups work). Knock some down. How many are left? What's the number bond?
• Dice games: Roll two dice. Do they make 10? Make 7?

Use everyday moments

• "We need 10 plates. I've got 6. How many more do we need?"
• "There are 10 stairs. You've climbed 4. How many more to go?"
• "You have 20p. That costs 12p. How much change will you get?"

Quick-fire practice

Spend 2 minutes calling out numbers. "I say 3, you say...?" "7!" This is brilliant for building speed and automaticity. Do it in the car, while cooking, at bath time.

Spark Learn includes number bonds practice as part of its maths worksheets, generating fresh questions each time so your child gets plenty of varied practice without repetition.

Common struggles (and how to help)

"They still count on their fingers"

This is completely normal in Year 1. Fingers are a legitimate mathematical tool. The goal is to move towards instant recall over time, not to ban fingers immediately.

If your child is still counting on fingers for number bonds to 10 in Year 2, increase the frequency of quick-fire verbal practice. The repetition will build the automatic recall.

"They know them one way but not the other"

A child might know that 3 + 7 = 10 but struggle with 10 - 7 = ?. This is because they haven't yet internalised the relationship between the three numbers.

Part-whole models help here. Draw the circle with 10 at the top, 3 and 7 below. Point to any number and ask: what are the other two?

"They get them right sometimes but not consistently"

This means they're still learning, not that they've forgotten. Spaced repetition helps — brief practice every day rather than long sessions once a week.

Beyond number bonds to 10

Once number bonds to 10 are solid, your child will extend to:

• Number bonds to 20 (e.g., 13 + 7, 15 + 5)
• Number bonds to 100 using multiples of 10 (e.g., 30 + 70)
• Using number bonds for subtraction (e.g., knowing 6 + 4 = 10 means 10 - 6 = 4)

Each of these builds directly on the foundation of number bonds to 10. That's why getting those first bonds really solid is so important.

The takeaway

Number bonds aren't complicated. But they're genuinely important. A child who knows their number bonds fluently will find the rest of KS1 maths significantly easier.

The good news is that practising them doesn't require worksheets or textbooks. A few minutes of games, questions, and everyday maths will do the job beautifully.