# Number Sense: Fact Families (Addition and Subtraction)

Fact families are sets of problems and their inverses (so, 1+2=3, 2+1=3, 3-1=2, and 3-2=1). Because addition and subtraction problems are related, students really only need to memorize one set of facts to know 3 sets of facts. However, some students needs practice to see and understand how addition and subtraction problems relate to each other. This set of practice problems helps students build that understanding slowly, by first asking students to fill in blanks and then asking students to create entire fact families. Fact families focus on addition and subtraction facts up to 20.

*After reading the addition problems below, complete the related subtraction problems.*

4 + 5 = 9

So, 9 - 5 = _____

And, 9 - 4 = ______

*Based on the one problem shown, write the other three math problems that complete the fact family.*

6 + 2 = 8

___ + ___ = ___

___ - ___ = ___

___ - ___ = ___