Number Bonds & Fact Families Lab

Pick a whole number and split it into two parts. Discover all four related addition and subtraction facts, record your number bonds in a table, and find patterns in how numbers can be decomposed.

Guided Experiment: Number Bonds Investigation

Pick a number like 7. How many different ways do you think you can split it into two parts? Write your prediction.

Write your hypothesis in the Lab Report panel, then click Next.

Build a Number Bond

Whole Number
7
Part A
3
Part B
4
3 + 4 = 7. Parts match the whole!

Number Bond Diagram

7
3
4
Part APart B

Fact Family

Addition3 + 4 = 7
Addition (switched)4 + 3 = 7
Subtraction7 - 3 = 4
Subtraction7 - 4 = 3

Controls

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Reference Guide

What Is a Number Bond

A number bond shows how a whole number is made from two smaller parts. The whole sits at the top, and the two parts branch off below.

7 = 3 + 4

Any whole number can be split into many different pairs of parts. The number 7 can be split as 1+6, 2+5, 3+4, and more.

Fact Families

Every number bond gives you four related equations called a fact family. Two are addition facts and two are subtraction facts.

3 + 4 = 7
4 + 3 = 7
7 - 3 = 4
7 - 4 = 3

All four facts use the same three numbers. Knowing one fact in the family makes the others easier to remember.

Part-Part-Whole

Every addition or subtraction problem has a part-part-whole relationship. The two parts combine to make the whole.

Whole: the total amount
Part A: one smaller piece
Part B: the other smaller piece

If you know the whole and one part, you can always find the missing part by subtracting.

Why Fact Families Help

Learning fact families means you only need to memorize one bond to know four facts. Addition and subtraction are opposite, or inverse, operations.

Quick trick: If you know 6 + 4 = 10, then you already know 10 - 6 = 4 and 10 - 4 = 6.

Fact families also help with missing-number problems. If 5 + ? = 12, you can use 12 - 5 = 7 to find the answer.