To use fact families to learn the basic addition and subtraction facts.
A fact family is a group of math facts using the same numbers. In the case of addition/subtraction, you use three numbers and get four facts. For example, you can form a fact family using the three numbers 10, 2, and 12: 10 + 2 = 12, 2 + 10 = 12, 12 − 10 = 2, and 12 − 2 = 10.
We can use fact families to reinforce or learn the connection between addition and subtraction, and to help children memorize the basic addition & subtraction facts