# Lesson 8

Areas and Equivalent Expressions

These materials, when encountered before Algebra 1, Unit 6, Lesson 8 support success in that lesson.

### Lesson Narrative

In the associated Algebra 1 lesson, students expand expressions such as $$(x+3)(x+8)$$ by relating the expressions $$x+3$$ and $$x+8$$ to side lengths of a rectangle and using the distributive property. In this supporting lesson, students work with numerical expressions and reason about equal numerical expressions before representing side lengths with variables. Students make use of the structure of expressions and rectangles to reason about equivalent expressions (MP7).

### Learning Goals

Teacher Facing

• Identify and use the structure of expressions to multiply two numbers which can be written as sums.
• Understand, by writing different expressions to represent area diagrams, that expressions can look different but be equivalent.

### Student Facing

• Let’s write different expressions to represent the same area.

Building On

Building Towards