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.

$6 + 7$
$13 - 7$
$7 + 8$
$15 - 7$

Activity 1 Many Ways to Add and Subtract

Circle 1 addition expression and 1 subtraction expression.

$5 + 9$

$14 - 8$

$4 + 7$

$15 - 9$

$6 + 4 + 4$

$13 - 6$

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: