# Lesson 5

Expanded Form of Numbers

### Lesson Purpose

### Lesson Narrative

In previous lessons, students represented three-digit numbers by recording how many of each unit (for example, 357 as 3 hundreds, 5 tens, 7 ones). They also connected representations of a number using the fewest number of base-ten blocks to the value of the digits in three-digit numbers.

In this lesson, students extend their understanding of ways to express the value of the digits in three-digit numbers to include **expanded form**. They represent three-digit numbers as the sum of the value of each digit (for example, \(357 = 300 + 50 + 7\)).

- Action and Expression

- MLR8

### Learning Goals

Teacher Facing

- Read, write, and represent three-digit numbers using base-ten numerals and expanded form.

### Student Facing

- Let’s represent three-digit numbers as a sum of the value of each digit.

### Required Materials

Materials to Gather

### Required Preparation

Activity 2:

- Each group of 2 needs 3 number cubes.

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 20 min |

Activity 2 | 15 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

As students represented numbers in expanded form and as three-digit numbers, what evidence did you see that they understand place value?

### Suggested Centers

- Greatest of Them All (1–5), Stage 1: Two-digit Numbers (Supporting)
- Mystery Number (1–4), Stage 1: Two-digit Numbers (Supporting)