# Lesson 19

Use Properties to Multiply Decimals

### Lesson Purpose

The purpose of this lesson is for students to interpret and evaluate multiplication expressions with decimals and whole numbers.

### Lesson Narrative

In previous lessons, students used diagrams and expressions to articulate strategies for multiplying a whole number and a decimal. The purpose of this lesson is solidify this understanding as they match many different expressions for a single product and choose one to find the value. They think strategically about which expression to use. In previous lessons, the strategies included using whole number products and the associative property or using the distributive property. This lesson introduces one more strategy, compensation which is also an example of the distributive property. In the second activity, students choose from these different strategies to find the value of more complex products of a whole number and a decimal.
• Engagement

### Learning Goals

Teacher Facing

• Use properties of operations to interpret and evaluate multiplication expressions with decimals and whole numbers.

### Student Facing

• Let’s interpret and evaluate multiplication expressions with decimals and whole numbers.

### Required Materials

Materials to Copy

• Decimal Multiplication Expression Card Sort

### Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Activity 3 10 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

What did you say, do, or ask during the lesson synthesis that helped students be clear on the learning of the day? How did understanding the cool-down of the lesson before you started teaching today help you synthesize that learning?