Lesson 1 Sums and Differences Within 20

Warm-up Number Talk: Subtract Within 20

Find the value of each expression mentally.

Find the value of each sum mentally.
$6 + 6 =$
$9 + 9 =$
$7 + 7 =$
$8 + 8 =$
$5 + 5 =$
$9 + 8 =$
$7 + 8 =$
$8 + 5 =$
$6 + 5 =$
$7 + 6 =$
$7 + 9 =$
$6 + 8 =$
$9 + 2 =$
$7 + 5 =$
$8 + 4 =$
$2 + 9 =$
$9 + 7 =$
$6 + 9 =$
$8 + 3 =$
$9 + 4 =$
$8 + 6 =$
$3 + 9 =$
$5 + 6 =$
$9 + 5 =$
$5 + 9 =$
$9 + 6 =$
$8 + 9 =$
$6 + 7 =$
$5 + 7 =$
$8 + 7 =$
Circle any sum that you did not remember right away.
Write each sum you circled on an index card.
Use the index cards to work on building fluency with these sums.

Directions: