Lesson 2 Fluency Flip

- Let’s add and subtract fluently.

Warm-up True or False: Sums within 20

Decide if each statement true or false. Be prepared to explain your reasoning.

$8 + 5 = 8 + 2 + 5$
$8 + 5 = 8 + 2 + 3$
$8 + 5 = 10 + 3$

Activity 1 Heads Up: Make 20

Directions:

Partner A holds a card on their forehead without looking.
Partner B names the number that you can add to the number on the card to get 20.
Partner A says the number on their card.
Record an equation to represent how you found the unknown addend.

my equations	my partner’s equations

Activity 2 Number Mix Up

You are going to use your cards to complete number puzzles. You may only use numbers 0 through 9. You may only use each number one time to make all the equations true.