Math Background

Inverse Relationship Between Addition and Subtraction: When Students Ask

  • Why should I learn the facts?
    If you know one fact in a fact family, you can find the other facts. So if you forget one fact, you have a tool to find others.
  • How are facts related?
    They use the same three numbers.
  • Do all families have 4 facts?
    No, doubles have only two facts in their families; one addition fact and one subtraction fact.
  • What is a fact family?
    Addition and subtraction facts that belong together because they have all the same numbers make up a fact family.

Houghton Mifflin Math Grade 1