## Lesson: Inverse Relationship Between Addition and Subtraction

Introducing the Concept

Your children have been working with addition and subtraction facts. Today they are going to work with related facts.

**Materials:** 2 colors of counters, 10 of each; number cards 2 – 12 (or numbers the class is working with); paper and pencil

**Preparation:** Place the number cards facedown on a table along with the two colors of counters.

**Prerequisite Skills and Concepts:** Children should understand addition and subtraction. They should be able to add sums to 10 and subtract from 10 or less.

Review with children related facts. Have a volunteer draw a card and hold it up for the class to see. Have another volunteer take counters from both colors to equal the amount on the number card and place them in two groups. Ask the class to count how many counters in each group.