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What is a number bond? A parent’s guide

If your child’s homework shows a circle joined to two smaller circles, that is a number bond. It shows a whole number and two parts that make it, and it is how many schools teach adding and subtracting to 20.

By The Kizupi team · Written · Updated

Key findings

  • A number bond is a part-part-whole picture: a whole number in one circle, joined to the two parts that make it. Eureka Math uses the model from Kindergarten through Grade 5 [3].
  • Kindergarten standards ask children to break numbers up to 10 into pairs in more than one way, such as 5 = 2 + 3 and 5 = 4 + 1, and to find the number that makes 10 with any number from 1 to 9 [1].
  • In Grade 1, “making ten” is named as a strategy for adding within 20, as in 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14 [2].

What a number bond is

A number bond is a small drawing: one circle for the whole, joined by two lines to two circles for its parts. It says that the parts together make the whole.

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This one says 4 and 3 make 7. It also says 7 take away 4 is 3, and 7 take away 3 is 4. One picture holds a whole fact family, which is why teachers like it.

Why your child is asked to draw them

The standards ask children to take numbers apart. In Kindergarten, they “decompose numbers less than or equal to 10 into pairs in more than one way” and record each one with a drawing or an equation, and they find the number that makes 10 with any number from 1 to 9 [1]. A number bond is a drawing that does exactly that.

Eureka Math, a curriculum many US schools use, teaches the number bond in Kindergarten and keeps using it through Grade 5, later for tens, hundreds and fractions [3]. So the circles your first grader draws now will come back.

Example 1: a part is missing

7 and what make 10?

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Put 10 at the top and 7 in one part. The other part is what 7 needs to reach 10: 3. This is the question Kizupi’s Grade 1 drills ask over and over, “7 and what make ten?”, because knowing the pairs that make 10 by heart is what the next step needs.

Example 2: making ten to add 8 + 6

Grade 1 names this strategy: 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14 [2]. The number bond is how a child sees where the 2 and the 4 come from.

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8 needs 2 more to make 10, so split the 6 into 2 and 4. Give the 2 to the 8 to make 10, and 10 + 4 is 14. Kizupi’s hint for these is the same every time: “Make a ten first.”

Example 3: subtracting across ten, 13 − 4

The same idea runs backward. The standards’ own example is 13 − 4 = 13 − 3 − 1 = 10 − 1 = 9 [2].

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Split the 4 into 3 and 1. Take the 3 away first to land on 10, then 1 more to get 9. It looks longer than counting back, but it is far less error-prone than counting back four on fingers, and it works for every subtraction across ten.

How to help at home

  1. Start with real things. Seven crackers, split into two plates. Write the bond: 7 on top, the two plates below. Then split them another way.
  2. Find all the ways. 7 is 6 and 1, 5 and 2, 4 and 3. Kindergarten asks for “more than one way” [1], and it’s more fun as a hunt.
  3. Practice the tens. Say a number from 1 to 9, and your child says what makes 10 with it. A minute in the car is enough.
  4. Use it on a sum over 10. For 9 + 5, ask “what does 9 need to make 10?” and split the 5.

When the pairs come quickly, try the free Grade 1 addition and subtraction word problem sheets, each with a hint and an answer key. Our guide to tape diagrams covers the bar drawing that grows out of the same part-whole idea.

Questions parents ask

What is a number bond in first grade?

A drawing of a whole number and two parts that make it, such as 10 with 7 and 3. First graders use it to make ten when they add and subtract within 20 [2].

Is a number bond the same as a fact family?

They hold the same facts. The bond for 7, 4 and 3 gives 4 + 3 = 7, 3 + 4 = 7, 7 − 4 = 3 and 7 − 3 = 4, which is that fact family.

Why not just count on fingers?

Counting works for small numbers, but it is slow and easy to get wrong past 10. Knowing the pairs that make 10, and splitting a number to reach 10, is the strategy the Grade 1 standards name [2].

Do number bonds come back in later grades?

In Eureka Math, yes: the same model is used for tens and hundreds in Grade 2 and for fractions in Grades 3 to 5 [3].

Keep going

Sources

  1. Common Core State Standards Initiative, Kindergarten, Operations and Algebraic Thinking (K.OA). Read November 6, 2026.
  2. Common Core State Standards Initiative, Grade 1, Operations and Algebraic Thinking (1.OA). Read October 26, 2026.
  3. Great Minds (Eureka Math), The Number Bond: A K–5 Model That Fosters Number Sense (MaryJo Wieland, February 20, 2017). Read November 6, 2026.

Cite this page: The Kizupi team, “What is a number bond? A parent’s guide,” Kizupi, updated November 6, 2026, https://kizupi.com/guides/number-bonds.

Want a tutor that asks “how do you know?” every day? Kizupi’s pixel owl reads each problem aloud, hints one small step at a time and never hands over the answer. Grades 1–6.

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