# Lesson 9 Add 2 Two-digit Numbers

## Warm-up Number Talk: Make a Ten

Find the value of each expression mentally.

## Activity 1 How Did You Find the Value?

Find the value of .
Show your thinking using drawings, numbers, or words.

## Problem 1

Round 1:
Grab a handful of towers of ten and a handful of single cubes.

1. I have cubes and my partner has cubes.

2. How many cubes do you and your partner have altogether?
Show your thinking using drawings, numbers, or words.

## Problem 2

Round 2:

1. I have cubes and my partner has cubes.

2. How many cubes do you and your partner have altogether?
Show your thinking using drawings, numbers, or words.

## Problem 3

Round 3:

1. I have cubes and my partner has cubes.

2. How many cubes do you and your partner have altogether?
Show your thinking using drawings, numbers, or words.

## Problem 4

Round 4:

1. I have cubes and my partner has cubes.

2. How many cubes do you and your partner have altogether?
Show your thinking using drawings, numbers, or words.

## Problem 1

Find the value of .
Show your thinking using drawings, numbers, or words.