# Lesson 3 Add and Subtract Within 20

Let’s add and subtract within 20.

## Warm-up Number Talk: Use Known Sums

Find the value of each expression mentally.

## Activity 1 Many Ways to Add and Subtract

Circle 1 addition expression and 1 subtraction expression.

Find the value of the expressions in as many different ways as you can.

Show your thinking using drawings, number, or words.

## Activity 2 Heads Up

Write an equation for each round you play.

Round 1:

Round 2:

Round 3:

Round 4:

Round 5:

Round 6: