# Lesson 6

Write Expressions Where Letters Stand for Numbers

### Lesson Narrative

This lesson is a shift from previous work in this unit. Up until now, we were focused on writing and solving equations. Starting in this lesson, we begin to focus on writing expressions to represent situations. Students write expressions that record operations with numbers and with letters standing in for numbers. Students can choose to represent expressions with tape diagrams if they wish (MP5).

### Learning Goals

Teacher Facing

• Explain (orally) how to create and solve an equation that represents a situation with an unknown amount.
• Write an expression with a variable to generalize the relationship between quantities in a situation.

### Student Facing

Let's use expressions with variables to describe situations.

### Student Facing

• I can use an expression that represents a situation to find an amount in a story.
• I can write an expression with a variable to represent a calculation where I do not know one of the numbers.