# Lesson 2

Make Hundreds

## Warm-up: Choral Count: Count by 10 (10 minutes)

### Narrative

The purpose of this Choral Count is for students to practice counting by 10 beyond 120 and notice patterns in the count. These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to recognize multiples of 100 written as numerals and make connections between groups of 10 tens and hundreds.

### Launch

• “Count by 10, starting at 0.”
• Record as students count. Record 10 numbers in each row. Then start a new row directly below.
• Stop counting and recording at 300.

### Activity

• “What patterns do you see?”
• 12 minutes: quiet think time
• Record responses.

### Activity Synthesis

• “Who can restate the pattern in different words?”

## Activity 1: Make Hundreds (20 minutes)

### Narrative

The purpose of this activity is for students to use groups of 10 tens to compose multiples of 100. Students use base-ten blocks to make a group of 10 tens and exchange it for 1 hundred. They find the total number of tens and represent the same quantity with hundreds. When students make connections between the number of tens and hundreds they need to represent each number and the digits in the three-digit number, they look for and express regularity in repeated reasoning (MP8).

If you do not have enough base-ten blocks for groups of 4, you can make larger groups of students to use fewer blocks.

MLR8 Discussion Supports. Synthesis: At the appropriate time, give students 2–3 minutes to make sure that everyone in their group can explain what they notice about the number of tens and the number of hundreds in each problem. Invite groups to rehearse what they will say when they share with the whole class.

### Required Materials

Materials to Gather

### Required Preparation

• Each group of 4 students will need at least 50 ten blocks. Do not include hundreds blocks for this activity.

### Launch

• Groups of 4
• Give each group at least 50 base-ten blocks.
• “Yesterday, we looked at different ways to represent 100 with tens, ones, and as 1 unit called a hundred.”

### Activity

• “Today, we are going to use base-ten blocks to represent numbers that are larger than 100.”
• “Work with your group to represent the numbers shown with your base-ten blocks.”
• 10 minutes: small-group work time
• Monitor for groups that discuss ways to represent 300 by:
• using base-ten blocks and organizing into groups of 10 tens
• reasoning that if 1 hundred is 10 tens, then 2 hundreds is 20 tens, and 3 hundreds is 30 tens
• connecting patterns in the number of tens to the numerals and digits.

### Student Facing

1. Build each number using base-ten blocks. Record how many tens blocks you use.

1. Build 90.

2. Build 110.

3. Build 150.

____________ tens

____________ tens

____________ tens

2. How many base-ten blocks would you need to build 200?

____________ tens

3. How many base-ten blocks would you need to build 300?

____________ tens

4. How many base-ten blocks would you need to build 300 if you could use 1 hundreds block?

1 hundred ____________ tens

5. How many tens would you need to build 300 if you could use 2 hundreds blocks?

2 hundreds ____________ tens

6. How many tens would you need to build 300 if you could use only hundreds blocks?

____________ hundreds ____________ tens

### Activity Synthesis

• Invite previously identified students to share how they reasoned about ways to represent 300.
• “What did you notice about the number of tens and the number of hundreds?” (10 tens = 1 hundred, 20 tens = 2 hundreds, 30 tens = 3 hundreds)
• “How many hundreds would I have if I have 80 tens?” (8 hundreds)

## Activity 2: How Many Hundreds? (15 minutes)

### Narrative

The purpose of this activity is for students to make sense of representations of more than 1 hundred. Students recognize that base-ten diagrams can be used to represent hundreds even when all of the ones are not outlined. Students make connections between multiples of 10 and multiples of 100, as they consider the relationship between 70 tens and 7 hundreds. Students describe how grouping tens and counting units of 1 hundred help to count and represent large numbers.

Action and Expression: Internalize Executive Functions. Synthesis: Check for understanding by inviting students to rephrase how ones, tens, and hundreds can all be used to represent the number 700 in their own words. Keep a display of their responses to reiterate this content.
Supports accessibility for: Memory, Organization

### Required Materials

Materials to Gather

• Groups of 24

### Activity

• “Han and Jada represented 700 using base-ten blocks, numbers, and words.”
• “They were both going to draw a base-ten diagram, but ran out of time.”
• “Represent each student’s work with base-ten blocks in your group.”
• “Then, discuss each question together.”
• 10 minutes: group work time
• Monitor for groups that organize their tens into groups of ten and count each group as 1 hundred.

### Student Facing

Han and Jada represented the same number using base-ten blocks. They started base-ten diagrams, but ran out of time to finish them.

Han

I only used hundreds.

I only used tens.

Total value: 700

Total value: 700

1. Use base-ten blocks to show what each student’s work would look like if they had time to finish it.

2. Explain how you know both ways of using base-ten blocks show 700.
4. Explain why you think Han ran out of time to finish his diagram.

### Student Response

If students count out 70 tens to show Han’s work, but do not organize the tens into groups, consider asking:
• “What is the value of all these tens? How can you prove that?”
• “How could you organize the tens so it’s easier to see the total value?”

### Activity Synthesis

• “How do you know that Jada’s way shows 700?” (You could count each hundred block by 1. You could count the squares by 1. If there are 7 hundred blocks, then it shows 700.)
• Invite previously selected identified groups to share how they organized their blocks when using Han’s way.

## Lesson Synthesis

### Lesson Synthesis

“Today we used base-ten blocks and diagrams to represent numbers that are much greater than 100.”

“Which way do you think was easier to represent 700, Jada’s way or Han’s way? Explain.” (Jada’s way. It’s faster to just count out 7 blocks than 70 blocks. It was easier to make sure we were showing 700.)

“Han’s way used 70 total blocks. How could you represent 700 with the greatest amount of blocks?” (You could use 700 ones.)