# Lesson 20

More or Less than 10?

### Lesson Purpose

The purpose of this lesson is for students to estimate whether a group has more or fewer than 10 objects or images.

### Lesson Narrative

In previous lessons and units, students represented 10 in many different ways and used these representations to compose and decompose 10. In this lesson, students use their understanding of 10 to estimate how many images there are. Students also assess the reasonableness of given estimates. The focus on understanding the magnitude of 10 prepares students for work with place value in the base-ten system in grade 1.

If students need additional support with the concepts in this lesson, refer back to Unit 6, Section B in the curriculum materials.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Estimate whether a group has more or fewer than 10 objects or images.

### Student Facing

• Let’s decide if there are more or fewer than 10 things in a group.

### Required Materials

Materials to Gather

### Required Preparation

Activity 3:

• Gather materials from:
• Shake and Spill
• Number Race
• Grab and Count
• What's Behind My Back?
• Pattern Blocks

### Lesson Timeline

 Warm-up 10 min Activity 1 10 min Activity 2 10 min Activity 3 25 min Lesson Synthesis 5 min Cool-down 0 min

### Teacher Reflection Questions

In grade 1, students learn that a group of 10 ones makes a new unit called a ten. How has this work prepared students to understand 10 ones as 1 new unit?