standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Narrative
The purpose of this activity is for students to compare decimals using the context of distance. Students should have access to hundredths grids, if they choose to use them. Monitor for students who compare the decimals using
place value reasoning to compare the 1 tenth for Diego's throw with the 1 hundredth for Jada's throw
hundredths grids for the decimal part of the throws
number lines, recalling work from a previous course
When students decide to compare the decimals using number lines or hundredths grids, they are using appropriate tools strategically (MP5).
MLR8 Discussion Supports.
Encourage students to begin partner discussions by reading their written responses aloud. If time allows, invite students to revise or add to their responses based on the conversation that follows.
Advances: Conversing, Speaking
Required Materials
Materials to Copy
Small Grids
Launch
Groups of 2
Display the image in student workbook.
“Have you ever thrown a frisbee?”
Poll the class.
“A frisbee is a disc. In the Olympics, there is an event called the discus throw. Participants try to throw a metal disc as far as they can.”
Activity
2 minutes: independent work time
5 minutes: partner work time
Monitor for students who use reasoning named in the activity narrative.
Student Facing
Diego and Jada were competing to see who could throw the frisbee further. Diego threw the frisbee 5.10 meters. Jada threw the frisbee 5.01 meters.
Who threw the frisbee further?
Be prepared to explain your thinking.
[IMG]
Tyler and Han were competing to see who could swim the length of the pool faster. Tyler swam the length of the pool in 35.15 seconds. Han swam the length of the pool in 35.30 seconds. Who swam the length of the pool faster? Be prepared to explain your thinking.
Student Response
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Activity Synthesis
Ask previously selected students to share their solutions.
“Both problems are about comparing decimals. How are the problems different?” (The units are different in the two problems. One is meters and the other is seconds. In one problem, the winner has the greater number and in the other problem, the winner has the lesser number.)


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