Lesson 7
Meters and Centimeters
Warmup: Notice and Wonder: Big Bug, Little Bug (10 minutes)
Narrative
The purpose of this warmup is to elicit what students know about length measurement and about units of measurement. While no unit is specified for the ruler in the image, students are likely to bring up centimeters (given the way each 1 unit is partitioned into 10 smaller parts, as seen on centimeter rulers). The work here prepares students to think about the relationship between meters and centimeters later in the lesson.
Launch
 Groups of 2
 Display the image.
 “What do you notice? What do you wonder?”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 1 minute: partner discussion
 Share and record responses.
Student Facing
What do you notice? What do you wonder?
Student Response
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Activity Synthesis
 Consider sharing that the large insect is a stick insect. (The longest species ever found measured more than 60 cm.) The small insect is a green potato bug.
 “If each unit in the ruler is 1 centimeter, about how long is the potato bug?” (1 cm) “What about the stick insect?” (About 16 cm with the antennae, about 12 cm otherwise.)
Activity 1: How Long is One Meter? (25 minutes)
Narrative
The purpose of this activity is for students to develop an intuition of 1 meter as 100 times as long as 1 centimeter. Students build a 1meter long strip out of centimeter grid paper. They use this tool to identify objects or distances that are about 1 meter long.
Advances: Speaking, Conversing, Representing
Required Materials
Launch
 Groups of 3–4
 Give each group 2–3 sheets of centimeter grid paper, 2–3 pairs of scissors, and some tape.
 “Each grid on the paper is 1 centimeter long.”
 “Work with your group to cut the centimeter grid paper into strips and then join them to make a strip of paper that is exactly 1 meter long.”
Activity
 “After your 1meterlong strip is made, identify some objects in the classroom or some distances you think are about 1 meter long. Then, use your tool to check your predictions.”
 15 minutes: group work on the first two problems
 2–3 minutes: independent work on the last problem
Student Facing

Use the centimeter paper to build a strip that is 100 centimeters long. You will need scissors and tape.
If you do it precisely, your paper strip will be 1 meter long.

List 5 items in the classroom that you think are about 1 meter long.
Then, use your paper strip to check how close your prediction is to 1 meter.

Decide whether each of the following is more than 1 meter, less than 1 meter, or about 1 meter.
 The stick insect in the warmup activity
 The step you make when walking
 The step you make when running
 Your arm span
Be prepared to explain how you know.
Student Response
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Advancing Student Thinking
Students may make a counting error and put together a strip that is shorter or longer than 1 meter. Consider asking:
 “How did you organize and count the centimeter pieces?”
 “How can you make sure there are 100 centimeter pieces? Can grouping the pieces help?”
Activity Synthesis
 Invite groups to share their predictions and the results of their measurement.
 Select students to share their responses to the last problem. If time permits, allow students to measure the arm span or step length of a few students.
 “How many 1 centimeter grid squares did you put together to make 1 meter?”
Activity 2: In and Around the School (10 minutes)
Narrative
In this activity, students analyze student work converting meters to centimeters to develop the understanding that a meter is “100 times as long” as a centimeter. They correct errors in reasoning centering around place value (MP3).
Supports accessibility for: Conceptual Processing, VisualSpatial Processing
Launch
 Groups of 2
 Read the opening paragraph as a class. Ask 1–2 students to reframe the context in their own words.
Activity
 “Take 5 quiet minutes to spot and correct Priya’s errors and find the missing measurement. Then, share your thinking with your partner.”
 5 minutes: independent work time
 3–4 minutes: partner discussion
 Monitor for students who place zeros for the measurement in centimeters and those who explicitly reason in terms of 100 times the value in meters.
Student Facing
Priya took some measurements in meters and recorded them in the table, but she made some errors when converting them to centimeters. She also left out one measurement.
measurement in meters  measurement in centimeter  

a. height of door  2  200 
b. height of hallway  3  30 
c. width of hallway  5  500 
d. length of gym  18  180 
e. length of hallway  27  2,700 
f. length of playground  50 
 Find and correct Priya’s conversion errors. Be prepared to explain how you know.
 Fill in the length of the playground in centimeters. Write an equation to represent your thinking.
Student Response
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Advancing Student Thinking
Activity Synthesis
 See lesson synthesis.
Lesson Synthesis
Lesson Synthesis
“Today we looked at centimeters and meters and related them to our multiplication work.”
“Write one sentence to describe the relationship between the two units. Be as specific and precise as you can in your word choice.”
While students’ statements may emphasize the equivalence of 1 meter and 100 centimeters (“one meter is 100 centimeters”), highlight explanations that articulate the multiplicative relationship of the two units (“1 meter is 100 times as long as 1 centimeter”).
Display the table showing Priya’s measurements. Invite students to share their responses to the last activity.
Reiterate the multiplicative relationship of the values in the two columns, revoicing students’ responses as needed. (For instance, “If 1 meter is 100 times 1 centimeter, then 3 meters must be \(3 \times 100\) centimeters or 300 centimeters, rather than 30 centimeters.”)
Cooldown: The Longest Creatures (5 minutes)
CoolDown
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