# Lesson 10

Place Value and the Number Line

### Lesson Purpose

The purpose of this lesson is for students to compare representations of addition and subtraction methods represented on the number line.

### Lesson Narrative

In previous lessons, students matched addition and subtraction equations and their representations on a number line. They found the value of differences within 100 and represented their thinking on a number line.

In this lesson, students add and subtract within 100 and represent computation methods on a number line. They compare representations of methods based on place value and make connections across representations (MP2). The expressions in each activity include numbers that elicit methods based on counting on or counting back by place.

• Representation
• MLR8

### Learning Goals

Teacher Facing

• On a number line, represent place value methods for solving addition and subtraction equations that do not require decomposing a ten.

### Student Facing

• Let’s compare methods using the number line.

### Required Materials

Materials to Gather

### 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

Why is it important for students to be able to represent their thinking and strategies using varied representations? How can you support students to feel comfortable using other representations?

### Suggested Centers

• Number Puzzles: Addition and Subtraction (1–4), Stage 4: Within 100 with Composing (Addressing)
• Number Line Scoot (2–3), Stage 1: Twos, Fives, and Tens (Addressing)