Same Math › Grades K–2 › Number bonds
What is a number bond?
A number bond shows how one number splits into two parts. Your child's class uses it to see that 10 is also 7 and 3, which later makes adding and subtracting in their head much faster.
- The whole sits on top. It's the total.
- The parts hang below. Together they make the whole.
- Read it three ways: 7 + 3 = 10, 10 − 3 = 7, 10 − 7 = 3.
Why schools teach it
It's the step before "making ten"
Most of us learned 8 + 5 = 13 by memorizing it or counting on our fingers. Number bonds teach kids to break numbers apart instead, so 8 + 5 becomes 8 + 2 + 3: first get to 10, then add what's left. By first grade, this "make a ten" strategy is part of the standards, and it's how many classes now teach mental math.
It also links adding and subtracting. A child who sees 10 as 7 and 3 knows 10 − 7 without having to learn it as a separate fact.
At the kitchen table
What to say, and what to skip
Say this
What's the whole? Where does it go?
If one part is 7, how many more do we need to make 10?
Can you find another way to split 10?
There are six ways if you count 10 and 0. Finding them is the point.Show me with your fingers or some coins.
Objects are fine. Counting is how this starts.
Skip this
Just add them, it's the same thing.
It isn't for them yet. The bond is how they see that addition and subtraction are linked.Here, I'll show you the faster way.
Showing your column method now can confuse the class strategy. Ask the teacher before teaching shortcuts.- Calling the top circle "the answer."Use "whole" and "parts," the same words the class uses.
See it in action
How a first grader solves 8 + 5
Ask what 8 needs to make 10
8 + 2 = 10Split the 5 into 2 and 3 with a bond
Make ten, then add what's left
8 + 2 = 10, 10 + 3 = 13
It looks slower than "8 + 5 = 13." It's training the move kids will use for 38 + 5, 98 + 7 and beyond.
Free practice sheet
Make a number bond sheet
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Parents also ask
My child already knows 7 + 3. Why draw circles?
Knowing the fact and seeing how numbers break apart are different skills. The bond builds the second one, which makes bigger mental math possible later.
Is a number bond the same as a fact family?
They're close cousins. A fact family lists the four equations (7 + 3, 3 + 7, 10 − 3, 10 − 7). A number bond is the picture that holds all four at once.
Can the parts be the same number?
Yes. 10 splits into 5 and 5. Zero works too: 10 and 0.
What comes after number bonds?
Making ten (shown above), then the same idea with bigger numbers, like splitting 47 into 40 and 7.