Lesson 3
Compose Threedigit Numbers
Lesson Purpose
Lesson Narrative
In previous units, students used baseten blocks and diagrams to compose and decompose tens when adding and subtracting by place. In previous lessons, students learned that a hundred is a unit that is made up of 10 tens and used baseten blocks to show composing a hundred with 10 tens.
In this lesson, students represent threedigit numbers that include an amount of hundreds, tens, and ones. In the first activity, students take inventory of the units represented by a collection of baseten blocks. They use their understanding of the units of hundred and ten to determine how to represent the total value with the fewest number of blocks possible. In the second activity, students use baseten diagrams to represent values using the fewest number of each unit possible and connect these representations to the meaning of each digit in a threedigit numeral. In both activities, look for the different ways students represent and record the value of their blocks for reference in the activity syntheses and in future lessons.
 Engagement
Learning Goals
Teacher Facing
 Compose threedigit numbers using place value understanding.
Student Facing
 Let’s compose threedigit numbers.
Required Materials
Materials to Gather
Required Preparation
Activity 1:
 Each group of 3–4 students will need a container with 2 hundreds, 28 tens, and 15 ones.
 Each group of 3–4 students will need access to additional baseten blocks (hundred blocks and ten blocks).
CCSS Standards
Addressing
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
Suggested Centers
 Greatest of Them All (1–5), Stage 1: Twodigit Numbers (Supporting)
 Mystery Number (1–4), Stage 1: Twodigit Numbers (Supporting)
Print Formatted Materials
For access, consult one of our IM Certified Partners.
Additional Resources
Google Slides  For access, consult one of our IM Certified Partners. 

PowerPoint Slides  For access, consult one of our IM Certified Partners. 