# Lesson 1 Compare, Count on, and Count Back

Let’s compare numbers and add or subtract.

## Warm-up Number Talk: Count Back

Find the value of each expression mentally.

## Activity 1 Notice the Difference

## Problem 1

Tyler and Elena were asked to find the value of

Their work is shown.

Tyler

Elena

What do you notice? What do you wonder?

## Problem 2

Locate and label 203 and 198 on the number line.

Compare using >, <, or =.

Find the value of

. Show your thinking.

## Problem 3

Locate and label 673 and 680 on the number line.

Compare using >, <, or =.

Find the value of

. Show your thinking.

## Problem 4

Locate and label 501 and 499 on the number line.

Find the value of

. Show your thinking.

## Problem 5

Find the value of

## Activity 2 What’s the Big Difference?

## Problem 1

Fill in the missing numbers.

Does this number line show counting on by 10 or counting on by 100?

## Problem 2

Fill in the missing numbers.

Does this number line show counting on by 10 or counting on by 100?

## Problem 3

Fill in the missing numbers.

Does this number line show counting on by 10 or counting on by 100?

## Problem 4

Fill in the missing numbers to show counting on by 10.

739, 749, , 769,

Explain how you can tell your numbers show counting on by 10 and not counting on by 100.

## Practice Problem

## Problem 1

Find the value of each difference. Show your thinking.