# Lesson 17

Sums of Tenths and Hundredths

### Lesson Purpose

The purpose of this lesson is for students to use equivalent fractions to add tenths and hundredths, where the sum is greater than 1.

### Lesson Narrative

Prior to this lesson, students learned to combine tenths and hundredths up to a sum of 1. In this lesson, they extend that work to include larger fractions and continue to build their ability to identify equivalent fractions that are helpful for finding sums.

They also encounter some equations involving unknown addends. While subtracting tenths and hundredths is not an expectation at this point, students can reason about the unknown addends by relying on their understanding of addition, their experience with decomposing a fraction into a sum, and their knowledge of equivalence.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Use equivalent fractions to add tenths and hundredths, where the sum is greater than 1.

### Student Facing

• Let’s add more tenths and hundredths.

### Required Materials

Materials to Gather

Materials to Copy

• Fraction Action: Tenths, Hundredths
• Card Sort: Less Than, Equal to, or Greater Than 1

### Required Preparation

Activity 1:

• Create a set of cards from the blackline master for each group of 2-4 students.

Activity 3:

• Create a set of cards from the blackline master for each group of 2.

Building On

### Lesson Timeline

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

### Teacher Reflection Questions

What questions that you asked supported students’ thinking about equivalence and addition of fractions today? What did students say or do that showed they were effective?