# Lesson 13

Using Decimals in a Shopping Context

### Lesson Narrative

In previous grades, students learned how to add, subtract, multiply, and divide whole numbers and decimals to the hundredths place. In this unit, they will extend this knowledge to include to all positive decimals.

This lesson activates students’ previous experiences with the four operations, all in the context of planning for a party while staying within a budget (MP4). To do so, students make reasoned estimates and then compare them to actual calculated values. The lesson offers insights into students' understanding of operations and the structure of base-ten numbers before new concepts are introduced.

### Learning Goals

Teacher Facing

• Calculate sums and products of decimals in the context of money, and explain (orally and in writing) the calculation strategy
• Estimate sums, differences, products, and quotients of decimals in the context of money, and explain (orally) the estimation strategy.

### Student Facing

Let’s use what we know about decimals to make shopping decisions.

### Required Preparation

Pick up newspaper circulars from a local grocery store for students to use. Prepare enough for each group of 2 students to have a copy. Alternatively, prepare access to grocery advertisements online.

### Student Facing

• I can use decimals to make estimates and calculations about money.

Building On