Lesson 10

The purpose of this lesson is for students to add three-digit numbers using strategies based on place value and the properties of operations.

In previous lessons, students used properties of operations, their understanding of the count sequence, and their understanding of place value to add within 1,000. They used different methods and representations to add by place and compose tens and hundreds.

In this lesson, students choose their own methods for adding within 1,000 and share their methods with their peers. They also have opportunities to explain why they chose their methods based on the numbers in an expression. They also analyze the relationship between two numbers in an equation to find an unknown value. Students use what they know about composing units to find unknown three-digit numbers when they are partially covered.

• Create a set of cards from the blackline master for each group of 2. 

Unlike talking, listening is a difficult thing to observe. At what points in the lesson did you observe students listening to one another’s ideas today in class? What indicators do you have that they were listening?