Curriculum  /  Math  /  5th Grade  /  Unit 6: Multiplication and Division of Decimals  /  Lesson 18

Multiplication and Division of Decimals

Lesson 18

Math

Unit 6

5th Grade

Lesson 18 of 23

Objective

Solve real-world problems involving multiplication and division with decimals.

Common Core Standards

Core Standards

  • 5.NBT.B.7 — Add, subtract, multiply, and divide decimals to hundredths, 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.
  • 5.OA.A.1 — Use parentheses, brackets, or braces in numerical expressions, and evaluate expressions with these symbols.
  • 5.OA.A.2 — Write simple expressions that record calculations with numbers, and interpret numerical expressions without evaluating them. For example, express the calculation "add 8 and 7, then multiply by 2" as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is three times as large as 18932 + 921, without having to calculate the indicated sum or product.

Criteria for Success

  1. Make sense of a three-act task and persevere in solving it (MP.1).
  2. Solve multi-step word problems involving all four operations, including those that require the interpretation of the remainder (MP.1, MP.4).
  3. Write an expression or equation to represent a real-world context, including using a letter to represent an unknown (MP.2).
  4. Assess the reasonableness of a solution by rounding to estimate or by checking a solution using multiplication (MP.1).
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Anchor Tasks

25-30 minutes

Problem 1

Act 1: Watch the video "Let It Flow (Act-1)".

a.   What do you notice? What do you wonder?

b.   How long will it take for the bottle to empty? Make an estimate. 

Guiding Questions

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Student Response

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References

Questioning My Metacognition Let It Flow — Act 1 video: Let it Flow (Act-1)

Let It Flow by Graham Fletcher is made available on Questioning My Metacognition under the CC BY-SA 4.0 license. Accessed April 1, 2019, 1:51 p.m..

Problem 2

Act 2: Use the following information to determine how long it will take for the bottle to empty:

  • The bottle holds 2 liters.
  • It takes 8.8 seconds to pour 0.08 liters of liquid, as seen in the video "Let It Flow (Act-2)".

Guiding Questions

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Student Response

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References

Questioning My Metacognition Let It Flow — Act 2 - Water Rate

Let It Flow by Graham Fletcher is made available on Questioning My Metacognition under the CC BY-SA 4.0 license. Accessed April 1, 2019, 1:51 p.m..

Problem 3

Act 3: Watch "Let It Flow (Act-3)" to see how long it took for the bottle to empty. 

Was your estimate reasonable? Why or why not?

Guiding Questions

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Student Response

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References

Questioning My Metacognition Let It Flow — Act 3 video: Let it Flow (Act-3)

Let It Flow by Graham Fletcher is made available on Questioning My Metacognition under the CC BY-SA 4.0 license. Accessed April 1, 2019, 1:51 p.m..

Problem 4

Act 4 (the sequel): Bella has 6.3 kilograms of berries. She packs 0.35 kilogram of berries into each container. She then sells each container for $2.99. How much money will Bella earn if she sells all the containers?

a.   Write an expression to determine how much money Bella will earn if she sells all the containers.

b.   Find the amount of money Bella will earn if she sells all the containers.

Guiding Questions

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Student Response

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Problem Set

15-20 minutes

Discussion of Problem Set

  • How much more money will Pinky earn than Miley in a month in #3? What does that make you think about the value of education?
  • How much money will Mr. Hower save if he pays cash in #4? What does that make you think about paying something in full versus in installments?
  • What expression did you write for #6(a)? Is there more than one possible correct answer? How do you know? What about #6(b)?

Target Task

5-10 minutes

A bank must have a security guard 24 hours a day. Five security guards split each day's time equally. If they each earn $7.25 per hour, how much will each guard earn each day?

Student Response

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Additional Practice

The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Multiplying Decimals

Topic B: Dividing Decimals

Topic C: Decimal Real-World Problems

Topic D: Measurement Conversion

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