Lesson 10
Place Value Comparisons (Part 1)
Warmup: Number Talk: Add Tens (10 minutes)
Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for mentally adding a multiple of 10 to a number. Building on their understanding of place value, students add tens to tens. When students notice that only the digit in the tens place is changing and make connections between the tens in each expression, they look for and make use of structure and express regularity in repeated reasoning (MP7, MP8). These understandings help students develop fluency and will be helpful in later lessons when students will add using strategies based on place value.
Launch
 Display one expression.
 “Give me a signal when you have an answer and can explain how you got it.”
 1 minute: quiet think time
Activity
 Record answers and strategy.
 Keep expressions and work displayed.
 Repeat with each expression.
Student Facing
Find the value of each expression mentally.
 \(36 + 40\)
 \(46 + 30\)
 \(59 + 40\)
 \(69 + 30\)
Student Response
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Activity Synthesis
 “How could the first expression help you find the value of the second one?” (46 is 10 more than 36, and 30 is 10 less than 40, so the answer is the same. They have the same number of tens.)
Activity 1: Compare by Place (15 minutes)
Narrative
The purpose of this activity is for students to learn that when comparing threedigit numbers, it is helpful to start by comparing the value of the hundreds. In this activity, the baseten diagrams are not organized by place and do not mirror the structure of a threedigit number. Students learn that when comparing numbers in which one number has more hundreds than the other, it is not necessary to consider the tens and ones.
Supports accessibility for: Memory, Conceptual Processing
Launch
 Groups of 2
 Display the image.
 “Who has more? How do you know?” (Tyler has 2 hundreds, but Mai only has 1. He has more.)
 30 seconds: quiet think time
 1 minute: partner discussion
 Share and record responses.
Activity
 “Today you will compare quantities represented by baseten diagrams.”
 “Compare the diagrams. Write the value of each quantity as a threedigit number and use the greater than, less than, or equal to symbols to compare the numbers.”
 8 minutes: independent work time
 “Compare with a partner.”
 2 minutes: partner discussion
Student Facing
Who has more? How do you know?
Compare the baseten diagrams.
Write each value as a threedigit number. Use the symbols \(<\), \(>\), or \(=\) to compare the numbers.

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\(\underline{\hspace{1.5cm}}\phantom{3}\boxed{\phantom{33}}\phantom{3}\underline{\hspace{1.5cm}}\)

\(\underline{\hspace{1.5cm}}\phantom{3}\boxed{\phantom{33}}\phantom{3}\underline{\hspace{1.5cm}}\)
Student Response
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Advancing Student Thinking
 “How did you decide how to write each value as a threedigit number? How did you compare the numbers?”
 “Are there any units that have 10 or more?”
 “How did composing a new unit change your answer?”
Activity Synthesis
 Share responses for the first two comparisons.
 Consider asking:
 “How did you know your statement is true?”
 “What unit was most important in deciding which quantity was greater?”
 Display the images for \(224 = 224\).
 “Which value is greater? How do you know?” (The two quantities are equal. Both diagrams represent 224. One had 2 hundreds, but the other had 1 hundred and 12 tens.)
 Record \(224 = 224\).
 “When comparing numbers based on baseten diagrams, what do you think about to help you decide which quantity is greater? Explain.” (First we need to find out how many hundreds each number has, but sometimes that means we have to count the tens to see if there are enough to make another hundred. If a number has more hundreds, we know that number is greater.)
Activity 2: Compare Hundreds, Tens, and Ones (20 minutes)
Narrative
The purpose of this activity is for students to extend their understanding of comparing threedigit numbers to include amounts in which the values in the hundreds place and tens place are the same in both numbers. In the last activity, students learned that by comparing the hundreds you can determine the greater value without considering the tens and ones. In this activity, they recognize the need to compare hundreds to hundreds, tens to tens, and ones to ones when the digits are the same in the numbers being compared.
Advances: Speaking
Launch
 Groups of 2
Activity
 “In the last activity we saw that if one number has more hundreds than another number it has the greater value.”
 “You will compare more quantities represented by baseten diagrams.”
 “Compare the diagrams. Write the value of each quantity as a threedigit number and use the greater than, less than, or equal to symbols to compare the numbers.”
 “Work with your partner to compare numbers and discuss your thinking for each problem.”
 15 minutes: partner work time
 Monitor for students who use precise language to explain how they knew that \(338 > 336\) based on comparing the value of each digit.
Student Facing
Compare the baseten diagrams. Write each value as a threedigit number. Use the symbols \(>\), \(< \), or \(=\) to compare the numbers.

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\(\underline{\hspace{1.5cm}}\phantom{3}\boxed{\phantom{33}}\phantom{3}\underline{\hspace{1.5cm}}\)

\(\underline{\hspace{1.5cm}}\phantom{3}\boxed{\phantom{33}}\phantom{3}\underline{\hspace{1.5cm}}\)

\(\underline{\hspace{1.5cm}}\phantom{3}\boxed{\phantom{33}}\phantom{3}\underline{\hspace{1.5cm}}\)
 In the last problem, how do you know which value was greater?
Student Response
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Activity Synthesis
 Invite previously selected students to share how they compared 338 and 336.
 Display 445 _____ 447.
 “Based on what you learned, how can you tell which number is larger without using the blocks?” (I can look at a number and see how many hundreds, tens, and ones there are without the diagrams.)
Lesson Synthesis
Lesson Synthesis
“Today, we compared threedigit numbers with the help of baseten diagrams.”
Display the image from the launch of the first activity.
“Tyler believes it is always better to compare numbers by starting with the ones, then tens, and then hundreds. Mai thinks it is better to start with the hundreds.”
”Who do you agree with? Explain your thinking to your partner.” (I think it depends. If there are more hundreds it’s easy to see who has more, but if the hundreds and the tens are the same we have to use the ones to decide who has more.)
Cooldown: Count and Compare (5 minutes)
CoolDown
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