# Lesson 15 Number Talk

Let’s create a Number Talk activity.

## Warm-up Number Talk: Addition

Find the value of each expression mentally.

## Activity 1 Number Talk Design 1

Here are three subtraction expressions.

Think of at least two different ways to find the value of each difference mentally.

Write a fourth subtraction expression whose value can be found using one of the strategies you thought of.

## Activity 2 Number Talk Design 2

Here are two addition expressions.

Think of at least two different ways to find the value of each sum mentally.

Write two more addition expressions whose value can be found using the strategies you thought of.

## Activity 3 Number Talk Design 3

Write three subtraction expressions to complete the Number Talk.

900 - 400

## Activity 4 Number Talk Design 4

Write four addition or subtraction expressions to create a Number Talk.