# Lesson 2

Multiplying Powers of Ten

### Lesson Narrative

Students make use of repeated reasoning to discover the exponent rule $$10^n \boldcdot 10^m = 10^{n+m}$$ (MP8). At this time, students develop rules for positive exponents. In subsequent lessons, students will extend the exponent rules to cases where the exponents are zero or negative. Students reason abstractly and quantitatively when applying exponent rules, pausing to consider the meaning of quantities, not just how to compute them (MP2).

### Learning Goals

Teacher Facing

• Generalize a process for multiplying exponential expressions with the same base, and justify (orally and in writing) that $10^n \boldcdot 10^m = 10^{n+m}$.

### Student Facing

Let’s explore patterns with exponents when we multiply powers of 10.

### Required Preparation

Create visual displays of the exponent rule $$10^n \boldcdot 10^m = 10^{n+m}$$ to be displayed for all to see throughout the unit. Here is a sample visual display:

### Student Facing

• I can explain and use a rule for multiplying powers of 10.

Building On