Fraction Operations

Lesson 7

Math

Unit 5

4th Grade

Lesson 7 of 21

Objective


Add two fractions where one denominator is a multiple of the other using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

Common Core Standards


Core Standards

  • 4.NF.B.3.A — Understand addition and subtraction of fractions as joining and separating parts referring to the same whole.
  • 4.NF.B.3.C — Add and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction.

Foundational Standards

  • 4.NF.A.1

Criteria for Success


  1. Make sense of a three-act task and persevere in solving it (MP.1).
  2. Add fractions where one denominator is a multiple of the other and where the sum is between 1 and 2, by replacing one fraction with an equivalent fraction in such a way as to produce an equivalent sum of fractions with like denominators.
  3. (Optional) Simplify solutions by rewriting them using the largest possible unit.

Tips for Teachers


  • This lesson goes beyond the explicit expectations of 4.NF.3. However, students will add fractions with denominators of 10 and 100 in Unit 6 (4.NF.5). Thus, today’s lesson is intended to prepare students for that work in Unit 6. The Progressions note that “students might encounter [such] situations, for example using a strip of paper or a tape diagram to reason that $$\frac{1}{3}+\frac{1}{6}=\frac{2}{6}+\frac{1}{6}=\frac{3}{6}=\frac{1}{2}$$” (NF Progression, p. 16).
  • In place of the Problem Set, you might decide to play the following NCTM Illuminations game, Fraction Game. This game can also be converted to a paper version if you don’t want to use the computer version.
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Anchor Tasks


Problem 1

Act 1: Watch the following video: Black box - Act 1.

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

b.   What will the sum of $$\frac{1}{2} + \frac{1}{4}$$ be?

Guiding Questions

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References

101Questions Black Box 2

Black Box 2 by is made available on 101Questions under the CC BY 3.0 license. Accessed July 17, 2018, 1:45 p.m..

Modified by Fishtank Learning, Inc.
YouTube Video: “Black box - Act 1” by msbritton215

“Black box - Act 1” by msbritton215 by msbritton215 is made available by YouTube under the Standard YouTube License. Accessed Oct. 23, 2019, 5:27 p.m..

Problem 2

Act 2: Use the following information to solve.

Guiding Questions

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References

101Questions Black Box 2

Black Box 2 by is made available on 101Questions under the CC BY 3.0 license. Accessed July 17, 2018, 1:45 p.m..

Modified by Fishtank Learning, Inc.

Problem 3

Act 3: Reveal the answer: Black box - Act 3. Was your answer reasonable? Why or why not?

Guiding Questions

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References

101Questions Black Box 2

Black Box 2 by is made available on 101Questions under the CC BY 3.0 license. Accessed July 17, 2018, 1:45 p.m..

Modified by Fishtank Learning, Inc.
YouTube Video: “Black box - Act 3” by msbritton215

“Black box - Act 3” by msbritton215 by msbritton215 is made available by YouTube under the Standard YouTube License. Accessed Oct. 23, 2019, 5:27 p.m..

Problem 4

Solve. Show or explain your work.

a.   $${{1\over2}+{1\over8}}$$

b.   $${{1\over5}+{3\over10}}$$

c.   $${{2\over3}+{1\over6}}$$

d.   $${{3\over4}+{5\over12}}$$

Guiding Questions

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References

EngageNY Mathematics Grade 4 Mathematics > Module 5 > Topic D > Lesson 21Concept Development

Grade 4 Mathematics > Module 5 > Topic D > Lesson 21 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by Fishtank Learning, Inc.
EngageNY Mathematics Grade 4 Mathematics > Module 5 > Topic D > Lesson 20Concept Development

Grade 4 Mathematics > Module 5 > Topic D > Lesson 20 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by Fishtank Learning, Inc.

Problem Set


Answer Keys

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Discussion of Problem Set

  • How did you determine which amounts could have been what Jake added to the jug in #1? 
  • In #2c, did you use sixths as the common denominator? Explain how thirds could be used as the common denominator. 
  • For #5, what strategies did you use to estimate if the sum would be between 0 and 1 or 1 and 2? 
  • Why is it important to have common denominators when adding fractions? 
  • How can you find the sum of two fractions without using a model? 
  • What benefit can you see in expressing a fraction as a mixed number or a mixed number as a fraction?

Target Task


Solve. Show or explain your work.

a.   $${{3\over10}+{2\over5}=}$$ _____

b.   $${{1\over2}+{5\over6}=}$$ _____

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.

Extra Practice Problems

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Word Problems and Fluency Activities

Word Problems and Fluency Activities

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Lesson 6

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Lesson 8

Lesson Map

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

Topic A: Building, Adding, and Subtracting Fractions Less Than or Equal to 1

Topic B: Building, Adding, and Subtracting Fractions Less Than 2

Topic C: Building, Adding, and Subtracting Fractions Greater Than or Equal to 2

Topic D: Multiplication of Fractions

Topic E: Line Plots

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