In this lesson, students practice using place value reasoning to compose and decompose units to find unknown numbers and to create equivalent forms of three-digit numbers. Students find the unknown numbers that make expressions equivalent and match expressions that represent the same number.

Although students should have access to base-ten blocks and tools to create base-ten diagrams as needed, students should also be encouraged to reason mentally based on their understanding of place value. The work of this lesson will support students’ work with adding and subtracting within 1,000 and developing fluency in adding and subtracting within 100.

The Cool-Down should be completed before the Lesson Synthesis so that students can share their responses during the Lesson Synthesis.

In future lessons, students will be working on developing fluency with addition and subtraction within 100. How does the work of this lesson support students in developing fluency with sums and differences within 100?