# Lesson 3

Properties of Exponents

These materials, when encountered before Algebra 1, Unit 5, Lesson 3 support success in that lesson.

### Lesson Narrative

The mathematical purpose of this lesson is for students to review the properties that $$x^a \boldcdot x^b = x^{a+b}$$, $$x^a \div x^b = x^{a-b}$$, and the convention for evaluating a number to the power of 0. The work of this lesson connects to previous work done in grade 8 when students learned each exponent rule and practiced applying them in creating equivalent expressions. This lesson prepares students to use exponents to rewrite expressions in the associated Algebra 1 lesson.

When students perform a number of numerical calculators and then express the outcome of $$3^a \boldcdot 3^b$$ and $$3^a \div 3^b$$ using a single exponent, they are expressing regularity in repeated reasoning (MP8). In the row game, when students get different answers for the same row, they have an opportunity to justify their thinking and critique the reasoning of others (MP3).

### Learning Goals

Teacher Facing

• Review properties of exponents.

### Student Facing

• Let’s recall the properties of exponents.