Lesson 1 Sums and Differences Within 20
Let’s find the value of sums and differences mentally.
Warm-up Number Talk: Subtract Within 20
Find the value of each expression mentally.
Activity 1 Check Yourself
Find the value of each sum mentally.
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.
Activity 2 Spin and Find the Missing Number
Spin the top spinner to get your total.
Spin the bottom spinner to get one addend.
Find the unknown addend.
Write an equation to show how you found the unknown addend.
my partner’s equations