# Lesson 3

Factors as a Factor in Our Strategy Choice

### Lesson Purpose

The purpose of this lesson is for students to reason about how the factors in a problem can influence the strategy they use to find the product, in particular identifying cases where the standard algorithm would be useful.

### Lesson Narrative

In previous units, students learned to use the standard algorithm to multiply multi-digit numbers and practiced using it in prior lessons. In this lesson, students reason about how the factors in a problem can influence the multiplication strategy they use. They recognize that the standard algorithm can be more useful in some cases than others. Each activity launches with an opportunity for students to review the problems before solving and the syntheses focus on student reasoning about their choices. It is important to note that there is not one correct strategy for each problem. If students need additional support with the concepts in this lesson, refer back to Unit 4, Section A in the curriculum materials.
• Action and Expression
• MLR7

### Learning Goals

Teacher Facing

• Fluently multiply multi-digit whole numbers using the standard algorithm.

### Student Facing

• Let's reason about strategies we use to multiply.

### Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

Through teaching, we have the opportunity to learn about our own understandings as well as those of the students. What is one thing you learned today about your own understandings and what is one thing you learned about the students?

### Print Formatted Materials

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