Unit 6, Lesson 21
Combining Like Terms (Part 2)
Grade 7
Preparation
Lesson Narrative
In this lesson, students analyze expressions that include parentheses and write equivalent expressions with fewer terms. First, students analyze some worked examples that contain errors and identify why the expressions are not equivalent. Then they match expressions that are equivalent. As students contrast different strategies for rewriting the same expression, they are critiquing the reasoning of others (MP3).
The last activity in this lesson is optional because it provides an opportunity for additional practice working with parentheses in expressions.
- Critique (in writing) methods for generating equivalent expressions with fewer terms.
- Identify equivalent expressions, and justify (orally and in writing) that they are equivalent.
Let’s see how to use properties correctly to write equivalent expressions.
Required Materials
Activity 1
Required Preparation
Access to index cards is suggested for students who need help isolating one expression at a time. They can use the index card to cover up nearby expressions.