# Lesson 18

### Lesson Purpose

The purpose of this lesson is for students to find the sum of three or more tenths and hundredths.

### Lesson Narrative

Previously, students learned to find sums of fractions with the same denominator and sums of tenths and hundredths. They added two or more tenths and hundredths, applying the commutative and associative properties along the way. This lesson prompts students to apply their understanding and skills to solve problems in context, and to practice finding sums of three or more tenths and hundredths (including mixed numbers).

• Representation
• MLR8

### Learning Goals

Teacher Facing

• Find the sum of three or more tenths and hundredths, using the commutative and associative properties strategically.

### Student Facing

• Let’s add tenths and hundredths again, more than two at a time.

### Required Materials

Materials to Gather

Materials to Copy

• More Than Two Fractions

### Required Preparation

Activity 1:

• Gather a few coins of different thicknesses for display.

Activity 2:

• Create six posters with an addition expression from the activity on each one.

Building On

### Lesson Timeline

 Warm-up 10 min Activity 1 25 min Activity 2 10 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

As you finish up this unit, reflect on the norms and activities that have supported each student in learning math. List the ways you have seen each student grow as a young mathematician throughout this work. List the ways you have seen yourself grow as a teacher. What will you continue to do and what will you improve upon in Unit 4?