Fact Families.

Fact Families

Do you know what a fact family is?
A fact family is a bunch of numbers that all work together… Here is an example: 6+4= =4 4+6= =6

In every fact family there are three numbers.
For example: 10 7 3 When you have a fact family, you have to use the same numbers all the time…

Or you can subtract the numbers…
You can add the numbers… 3+7=10 Or you can subtract the numbers… 10-7=3

When you add the numbers it doesn’t matter what order you add them.
The solution always comes out the same 7+3= =10

have to put the biggest number first…
When you subtract you ALWAYS have to put the biggest number first… 10-7= =7

1+2=3 2+1=3 3-1=2 3-2=1

3+2=5 2+3=5 5-2=3 5-3=2

What family number is missing?
1 3 ? 2 What family number is missing? How do you know? + + = 1 2 = 3 2 1 3 - - = 3 2 = 1 3 1 2

2 4 ? 2 What family number is missing? How do you know? + 2 2 = 4 - 2 4 2 =

1 4 ? 3 What family number is missing? How do you know? + - = 1 3 = 4 4 1 3 - + = 3 1 = 4 4 3 1

3 ? 6 3 What family number is missing? How do you know? + - = 3 3 = 6 6 3 3

4 ? 8 4 What family number is missing? How do you know? + - = 4 4 = 8 8 4 4

5 10 ? 5 What family number is missing? How do you know? + - = 5 5 = 10 10 5 5

8 16 ? 8 What family number is missing? How do you know? + + = 8 8 = 16 16 8 8

1 18 ? 17 What family number is missing? How do you know? + 18 + = 1 17 = 17 1 18 - = 17 - = 18 1 18 17 1

9 18 ? 9 What family number is missing? How do you know? + 18 - = 9 9 = 18 9 9

10 20 ? 10 What family number is missing? How do you know? + 20 - = 10 10 = 20 10 10

The End!

Presentation on theme: "Fact Families."— Presentation transcript: