Lesson 18
Make a Yard Stick (optional)
Warmup: Number Talk: Threes and Fives (10 minutes)
Narrative
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.
 \(3 + 5\)
 \(5  3\)
 \(5  3 + 5\)
 \(3 + 5 + 3 + 3\)
Student Response
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Activity Synthesis
 “What other numbers can we make with 3 and 5? Think of two other numbers you can make. You can use as many threes and fives as you like and you may subtract and add.”
Activity 1: Make a Yardstick (20 minutes)
Narrative
The purpose of this activity is for students to create and label the tick marks on a yard stick using what they know about length units, comparing length, and adding and subtracting length. They use the sides of a 3by5 inch index card to mark off all inch marks from 1 to 36. Students are invited to iterate the different sides of the index card along the paper forward and backwards. They look for ways to use what they know about the structure of a measuring tool, the known lengths of the index card, and what they know about adding and subtracting lengths to mark and label new tick marks (MP1, MP7).
Supports accessibility for: Organization, Memory
Advances: Speaking, Conversing, Representing
Required Materials
Materials to Gather
Required Preparation
 Cut the chart paper into strips. Each group of 2 needs a strip of paper that is at least 36 inches long and about 3 inches wide to make their yardstick.
Launch
 Groups of 2
 Give each group a strip of paper and an index card.
 “What do you know about a yardstick?”
 30 seconds: partner discussion
 Share responses.
 Display a yardstick and highlight that:
 a yardstick can be used to measure feet and inches
 a yardstick shows a total of 36 inches
Activity
 “Today you will use an index card to make a yardstick. The long side of the card measures 5 inches and the short side measures 3 inches.”
 “What numbers can you mark on the yardstick using the cards?”
 30 seconds: quiet think time
 1 minute: partner discussion
 “Tape the paper strip across your desk.”
 “One of you will hold the index card and the other will mark and label the units on the yardstick.”
 “Switch roles when you are about halfway done.”
 5 minutes: partner work time
 Monitor for students with different strategies. For example:
 students who initially use only one operation or number
 students who look for ways to add or subtract lengths using the card
 students who use the difference in the lengths of the short and long sides of the card
 students who discuss and use patterns in the differences between the tick marks they have made to find and label new tick marks
 “Now discuss your method with another group.”
 4 minutes: smallgroup discussion
Student Facing
Your teacher will give you a rectangle. The long side of the rectangle measures 5 inches and the short side measures 3 inches.
Use the card to make a yardstick that shows all inch marks from 1 to 36 inches.
Student Response
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Activity Synthesis
 Invite students to share their methods.
 Consider asking:
 “Which numbers did you mark first?”
 “Which numbers were easy to find?”
 “Which numbers were harder to find?”
 “Did you run into any problems? How did you solve them?”
Activity 2: Compare Yardsticks (15 minutes)
Narrative
Required Materials
Materials to Gather
Required Preparation
 Create a blank line plot with a scale that includes lengths longer, shorter, and equal to the height of student desks.
Launch
 Groups of 2
 Give each student a sticky note.
 Display the blank line plot.
Activity
 “Now, let's use the yardsticks we made to measure the height of our desks.”
 “Take turns measuring the height of your desk in inches. When you both agree, draw a big x on your sticky note and add your measurement to the class line plot.”
 2–3 minutes: partner work time
 Invite students to add their sticky note to the line plot.
 “Now, work together to answer the questions about our measurement data.”
 3–4 minutes: partner work time
 Monitor for students who notice the class got different measurements for the same object.
 Monitor for students who discuss reasons for the different measurements.
Student Facing
Measure the height of your desk using your yardstick.
Draw an x on your sticky note and add your measurement to the class line plot.
Use the completed line plot to answer the following questions:
 What do you notice? What do you wonder?
 What is the tallest measurement for the desks in the room?
 What is the shortest measurement?
 Find the difference between the tallest and the shortest measurements. Show your thinking.
Student Response
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Activity Synthesis
 Display a few studentcreated yardsticks next to each other for all to see.
 “What do you notice? What do you wonder?”
 If it does not come up, ask “How is it possible that different groups found different answers when they measured the same object?”
 “What could be a reason this happened?”
 uneven markings
 different use of yardsticks: straight, with slack, slanted
 different location of zero
 gaps or overlaps between inch marks
 Invite students to look at the displayed yardsticks and to see if they can see evidence for the reasons they gave.
 Highlight that it is important for a measuring tool to have equalsize units.
 If there is time, invite students to revise their yardstick markings. Alternatively, students can discuss which markings need revision.
 Invite students to explain how they revised their yardsticks with another group.
Activity 3: Measure Your Arms (15 minutes)
Narrative
In this activity, students use the yardsticks they made to measure the length of parts of their arms. They then use the measurements to write equations and describe what information the equations give about the situation (MP2, MP4).
Launch
 Groups of 2
 “You will use your yardsticks to measure parts of your partner's hand and arm.”
 Demonstrate the two lengths they will measure.
Activity
 10 minutes: partner work time
 Monitor for different equations using addition and subtraction.
Student Facing

Measure the length of your hands from the wrist to the top of your middle finger.
 hand length partner A: ____________
 hand length partner B: ____________

Measure the length of your forearms from the outside of your elbow to your wrist.
 forearm length partner A: ____________
 forearm length partner B: ____________

Write two equations using the measurements in your group and write two statements describing what the equations tell you.

Equation 1: ___________________________
Statement:

Equation 2: ___________________________
Statement:

Student Response
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Activity Synthesis
 Invite students to share their equations and statements.
 For each student that shares, consider asking:
 “Is there another way to describe what the equation tells us?”