standard_description: Interpret multiplication as scaling (resizing), by:
- Explaining why multiplying a given number by a fraction greater than 1 results in a product greater than the given number (recognizing multiplication by whole numbers greater than 1 as a familiar case); explaining why multiplying a given number by a fraction less than 1 results in a product smaller than the given number; and relating the principle of fraction equivalence a/b = (n×a)/(n×b) to the effect of multiplying a/b by 1.
- Comparing the size of a product to the size of one factor on the basis of the size of the other factor, without performing the indicated multiplication.
problem_activity: Narrative
The purpose of this activity is for students to convert from meters to centimeters using the context of a standing broad jump, a common test for physical fitness. Students may multiply by 100 to convert from meters to centimeters or divide by 100 to convert from centimeters to meters. Students should be encouraged to use whatever strategy makes sense to them. Future lessons will focus specifically on conversion from centimeters to meters. Give students access to meter sticks.
MLR8 Discussion Supports.
Synthesis: Provide students with the opportunity to rehearse what they will say with a partner before they share with the whole class.
Advances: Speaking
Required Materials
Materials to Gather
Metersticks
Launch
Groups of 2
Display the image from student workbook.
Give students access to meter sticks.
“What do you notice? What do you wonder?” (The girl is jumping. There are numbers on the mat. Did she start where the footprints are? How far did she jump?)
Activity
1–2 minutes: quiet think time
6–8 minutes: partner work time
Monitor for students who:
use their result for Tyler’s jump in centimeters to find his jump in millimeters
use the result in meters to find how far Tyler jumped in millimeters
Student Facing
[IMG]
[IMG]
Here are the distances that each student jumped.
{"table": [{"_attributes": {"border": "1"}, "thead": [{"tr": [{"th": [{"_attributes": {"scope": "col"}, "_value": "student"}, {"_attributes": {"scope": "col"}, "_value": "distance"}]}]}], "tbody": [{"tr": [{"td": [{"_value": "Mai"}, {"_value": "1.61 meters"}]}, {"td": [{"_value": "Tyler"}, {"_value": "1.43 meters"}]}, {"td": [{"_value": "Clare"}, {"_value": "1.57 meters"}]}]}]}]}
The average standing broad jump distance for 5th graders is 148 centimeters. Are each of the students in the table below, at, or above the average? Explain or show your reasoning.
The world record for the standing broad jump is 337 centimeters. Jada says that’s more than Mai and Clare jumped combined. Do you agree with Jada? Explain or show your reasoning.
Tyler says his jump sounds more impressive if he reports it in millimeters.
How far is Tyler’s jump in millimeters? What about Mai’s and Clare’s jumps?
Which unit do you think is best for reporting the jumps? Explain your reasoning.
Student Response
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Advancing Student Thinking
If students do not know the relationship between millimeters, centimeters, and meters, show them a meter stick and ask “How can you use the meter stick to figure out how many millimeters are in 1 meter?”
Activity Synthesis
Display the expression:
\(1.43 \times 100\)
.
“How does this expression represent Tyler’s jump in centimeters?” (There are 100 centimeters in a meter.)
Invite students to share how they found Tyler’s jump in millimeters.
Display the expression:
\((1.43 \times 100) \times 10\)
.
“In what unit of measurement does this expression represent Tyler's jump? How do you know?” (It represents Tyler’s jump in millimeters. There are 10 millimeters in a centimeter and
\(1.43\times100\)
represents the centimeters, so if we multiply the number of centimeters by 10, we will get the number of millimeters.)
Display the expression:
\(1.43 \times 1,\!000\)
.
“How does this expression represent Tyler’s jump in millimeters?” (There are 1,000 millimeters in a meter so I have to multiply by 1,000 to get millimeters from meters.)
Display the equation:
\(1.43 \times 1,\!000 = (1.43 \times 100) \times 10\)
.
Invite students to share which unit they prefer to express the distances that the students jumped.
“It’s important to choose a unit that makes sense to you.”


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