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Unit 5

Round Decimals

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Lesson 8

Place Value Patterns and Decimal Operations

Expressions and Equations

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Let’s round decimals to the nearest whole, tenth, and hundredth.

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Unit 5 ● Lesson 8

Learning

Goal

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Number Line

Unit 5 ● Lesson 8 ● Warm-up

What number might be represented on the number line?

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Record an estimate that is:

  • Would having tick marks for each tenth on the number line help improve your estimate? Why or why not?

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Estimation Exploration

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Name that Number

Unit 5 ● Lesson 8 ● Activity 1

Jada locates 15.53 on the number line. Do you think Jada accurately located the number? Explain your reasoning.

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Launch

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Name that Number

Unit 5 ● Lesson 8 ● Activity 1

A number is located between two tick marks on each number line. Label those tick marks and then estimate the number.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Name that Number

Unit 5 ● Lesson 8 ● Activity 1

  • How did you know how to label the tick marks?
  • How did you estimate the value of the number?
  • How did you estimate this number?

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Activity Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Which Number is Closest?

Unit 5 ● Lesson 8 ● Activity 2

  1. Round 6.273 to the nearest whole number, tenth, and hundredth. Use the number lines if they are helpful. Explain or show your reasoning.

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  • Round 4.158 to the nearest whole number, tenth, and hundredth.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Which Number is Closest?

Unit 5 ● Lesson 8 ● Activity 2

  • How did you round the number to the nearest whole number, tenth, and hundredth?
  • How did the number line help you round numbers?
  • How did thinking about the place and value of the digit help you round numbers?

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Activity Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Round the Numbers

Unit 5 ● Lesson 8 ● Activity 3

Round each number to the nearest whole number, tenth, and hundredth.

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nearest whole number

nearest tenth

nearest hundredth

34.482

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99.909

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5.555

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19.509

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Round the Numbers

Unit 5 ● Lesson 8 ● Activity 3

Let’s share different ways we rounded each number to the nearest whole number, tenth, and hundredth.

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Activity Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Round Decimals

Unit 5 ● Lesson 8

  • Today we rounded decimals to the nearest whole, tenth, and hundredth.

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Tyler said that 0.345 rounds to 0.3. Jada said 0.345 rounds to 0.35.

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  • Who do you agree with? Why?
  • Write three other numbers that round to 0.3 to the nearest tenth and three other numbers that round to 0.35 to the nearest hundredth.

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Lesson Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Round to the Nearest Tenth and Thousandth

Unit 5 ● Lesson 8

  1. Round 17.637 to the nearest tenth. Use the number lines if they are helpful.

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  • Round 17.637 to the nearest hundredth. Use the number lines if they are helpful.

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Cool-down

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.