Lesson 3
Choose Objects to Compare Length Indirectly
Warmup: Notice and Wonder: More Pencils (10 minutes)
Narrative
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 wonder?
Student Response
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Activity Synthesis
 “Which pencil is longer, A or C? How do you know?” (A is longer than B and C is shorter than B, so C is shorter than A.)
Activity 1: Mai and Clare Walk to School (15 minutes)
Narrative
The purpose of this activity is for students to compare two lengths indirectly. Since a third object is not given, students choose a third object strategically and share different ways to use a third object to compare (MP5).
Students choose from a variety of objects: connecting cubes towers, pieces of string, and unsharpened pencils. As students compare the length of the paths, students may use a single tool, such as a piece of string to compare the two paths. They may mark or cut the string. Some students may choose the tower of connecting cubes and determine that breaking off or counting the cubes is a way to determine whether one length is shorter or longer than the other. Others may select and try different tools until they find one that has a length that is in between the length of the two paths.
Required Materials
Materials to Gather
Required Preparation
 Each group of 2 needs:
 Connecting cubes in singles and towers of 10
 6inch and 10inch piece of string
 Unsharpened pencil
 Scissors
Launch
 Groups of 2
 Give students access to connecting cubes in towers of 10 and singles, string, unsharpened pencils, and scissors.
 “Clare and Mai walk to school every day. You can see their paths on the map. Who has the shorter walk? Choose a tool to use. Be ready to explain your thinking so that others will understand.”
Activity
 5 minutes: independent work time
 “Share your thinking with a partner.”
 2 minutes: partner discussion
 Monitor for students who use a single tool to compare the two paths and mark the tool to show one length, such as bending string or breaking off cubes to compare the other length.
Student Facing
Who has a shorter walk to school, Clare or Mai? How do you know?
Be ready to explain your thinking in a way that others will understand.
Student Response
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Advancing Student Thinking
If students use one object to match the length of Clare’s path and a different object to match Mai’s path, consider asking:
 “Tell me more about how you are using tools to figure out who has the shorter path.”
 “How could you use one tool to figure out who has the shorter path?”
Activity Synthesis
 Invite previously identified students to share.
 “How was using a tool helpful to compare the lengths of the paths?” (We couldn’t put the paths next to each other so it was helpful to have a tool that could be moved from one path to the other to compare.)
Activity 2: Will It Fit? (25 minutes)
Narrative
The purpose of this activity is for students to compare the length of two objects using a third object. When students decide if the teacher's desk will fit through the door or compare other large pieces of furniture, they will need to be precise about which lengths they are measuring as objects like the teacher's desk, a rug, and a bookcase, have a length, width, and in some cases a height (MP6). Next, they will need to select an appropriate third object to use to compare the lengths they have chosen. Teachers may choose to assign different questions for different groups to start with to facilitate student movement around the room. Teachers may also change any question that does not apply to their classroom.
Advances: Listening, Speaking
Supports accessibility for: Attention, SocialEmotional Functioning
Required Materials
Materials to Gather
Required Preparation
 Each group needs measuring materials from the previous activity.
Launch
 Groups of 2
 Give students access to measuring materials.
 “Have you ever seen someone move a large piece of furniture, like a couch, from one room to another? Is it easy to move big pieces of furniture? Why or why not?”
 30 seconds: quiet think time
 Share responses.
 “I have been thinking about getting a new desk. If I do, I will have to move this desk out of the room. I am not sure if this desk will fit through the door. How can we check to see if it will fit?” (We could measure with a string.)
 30 seconds: quiet think time
 1 minute: partner discussion
 Share responses.

“You are all going to check to see if my desk will fit through the door. You are also going to compare the length of some other objects in the room.”
Activity
 15 minutes: partner work time
 Monitor for a group that measures the width of the teacher's desk and one that measures the length.
Student Facing
 Will the teacher’s desk fit through the door?
Show your thinking using drawings, numbers, or words.
 Will a student desk fit through the door?
Show your thinking using drawings, numbers, or words.
 Which is longer, the bookshelf or the rug?
Show your thinking using drawings, numbers, or words.
 Which is longer, the file cabinet or the bookshelf?
Show your thinking using drawings, numbers, or words.
 Which is shorter, the bookshelf or the teacher’s desk?
Show your thinking using drawings, numbers, or words.
 Will the teacher’s desk fit next to the bookshelf?
Show your thinking using drawings, numbers, or words.
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 Invite previously identified students to share.
 For each student, ask: “How did they compare the length of the objects? What tool did they use? What part of each object did they measure?”
Lesson Synthesis
Lesson Synthesis
Cooldown: Unit 6, Section A Checkpoint (0 minutes)
CoolDown
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