Lesson objective: Write numbers in expanded form as a sum of hundreds, tens, and ones.

This lesson helps to build procedural skills with writing numbers in expanded form. Base ten blocks are used here because it supports understanding of how to decompose a number into hundreds, tens, and ones. This work develops students' understanding that we can represent a number in a variety of equivalent ways.

Students engage in Mathematical Practice 4 (Model with mathematics) as they use base ten blocks to help write other names for a number.

**Key vocabulary:**

- hundreds
- expanded form
- ones
- represent
- tens

**Special materials needed:**

- base ten blocks
- number cards (or number cubes or any random number generator)
- place value mat (optional)