Curriculum  /  Math  /  6th Grade  /  Unit 3: Multi-Digit and Fraction Computation  /  Lesson 7

Multi-Digit and Fraction Computation

Lesson 7

Math

Unit 3

6th Grade

Lesson 7 of 17

Objective

Add and subtract decimals using the standard algorithm.

Common Core Standards

Core Standards

  • 6.NS.B.3 — Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

Foundational Standards

  • 5.NBT.B.7

Criteria for Success

  1. Understand the role that place value plays in addition and subtraction of decimals. 
  2. Accurately use the standard algorithm to add and subtract decimals.
  3. Use addition and subtraction to solve decimal word problems.

Tips for Teachers

  • In fifth grade, students computed with decimals using all four operations and various strategies. In sixth grade, adding and subtracting with decimals is a fluency expectation. Use the problems in this lesson to review any strategies from fifth grade as needed so that students have a conceptual understanding to support the standard algorithm. Ensure students have opportunities to build towards fluency throughout the unit and the year. See our Guide to Procedural Skill and Fluency for additional information and strategies.

Lesson Materials

  • Graph Paper (2-3 sheets per student)
  • Optional: Calculators (1 per student) — Calculators can be used to check answers.
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Anchor Problems

25-30 minutes

Problem 1

Jayden has $20.56. He buys an apple for 79 cents and a granola bar for $1.76.

a.   How much money did Jayden spend?

b.   How much money does Jayden have now?

Guiding Questions

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Student Response

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References

Illustrative Mathematics Jayden's Snacks

Jayden's Snacks, accessed on Sept. 28, 2017, 2:25 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Problem 2

Dan is hiking along the Pacific Coast Trail. On Sunday morning, he hikes 5.83 miles before stopping for lunch. At the end of the day, Dan has hiked a total of 12.4 miles. How many miles did he hike after lunch? 

Guiding Questions

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Student Response

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Problem 3

The two problems below have been solved incorrectly. Explain the error in each problem and then correctly solve each one.

$${ 244.038+18.65 }$$ $${95.75-37.424}$$

Guiding Questions

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Student Response

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Problem Set

15-20 minutes

Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

Target Task

5-10 minutes

A pitcher of water holds 48.2 ounces of water in it. The water is poured into two glasses, 12.08 ounces into one glass and 18.86 ounces into a second glass.

a.   How much water is poured out of the pitcher?

b.   How much water is left in the pitcher?

Student Response

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Additional Practice

The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

  • Include fluency practice with adding and subtracting decimals.
  • Include error analysis problems of the standard algorithm applied incorrectly.

Word Problems and Fluency Activities

Next

Multiply decimals using strategies, and develop an understanding of the standard algorithm.

Lesson 8
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Lesson Map

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

Topic A: Dividing with Fractions

Topic B: Computing with Decimals

Topic C: Applying the Greatest Common Factor and the Least Common Multiple

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