5 th Grade Math Learning Objective: We will subtract fractions with unlike denominators. READY TO TEACH SM EDI ® Lessons ©2013 All rights reserved. EDI.

$Page 1: 5 th Grade Math Learning Objective: We will subtract fractions with unlike denominators. READY TO TEACH SM EDI ® Lessons ©2013 All rights reserved. EDI.$
CCSS 5th Grade Numbers and Operations – Fractions 1.2Add and subtract fractions with unlike denominators (including mixed numbers)

by replacing given fractions with equivalent fractions with like denominators.Lesson to be used by EDI-trained teachers only.

READY TO TEACHSM EDI® Lessons©2013 All rights reserved.

What are we going to do?

CFU

Students, you already know how to find the least common denominator of fractions. Now, we will use that skill to subtract fractions with unlike denominators.

Make Connection

The least common denominator (LCD) is the lowest multiple shared by a set of denominators.

We will subtract fractions with unlike denominators.

Learning Objective

Activate Prior Knowledge

2: 2, 4, 6, 8

1 1,

2 3

3: 3, 6, 9, 12

Find the least common denominator of the fractions below.

1. 2.

5: 5, 10, 15, 20 2: 2, 4, 6, 8, 10

3 1,

5 2

The LCD of and is 3.1

2

1

3The LCD of and is 10.

3

51

2

23

numerator

denominator

Fraction

CCSS 5th Grade Numbers and Operations – Fractions 1.2Subtract fractions with unlike denominators.

Lesson to be used by EDI-trained teachers only. ©2013 All rights reserved.

Which pair of fractions is ready to be subtracted? How do you know?

A

B

In your own words, how do you subtract fractions with unlike denominators? “To subtract fractions with unlike denominators ________.”

CFU

Concept Development

23

numerator

denominator

Fraction

Subtracting Fractions with Unlike Denominators

610

510

110

- =35

12

- =

35

The LCD of and12

is 10.

Equivalent Fractions

22

35

× 610

=55

12

× 510

=

- =

Fractions with unlike denominators have a different number of equal parts. Fractions with like denominators have the same number of equal parts. To subtract fractions, both fractions must have like denominators.

• To subtract fractions with unlike denominators use the least common denominator (LCD) to create equivalent fractions with like denominators.

23

25

23

13



1 equal value2 answer to a subtraction problem3 explain

Vocabulary

Skill Development/Guided Practice

Find the least common denominator. Hint: Find the lowest shared multiple.

Create equivalent1 fractions with like denominators. Hint: Use the least common denominator.

Subtract fractions. Hint: Subtract the numerators, keep the denominators the same.

Reduce the difference2, if possible.Interpret3 the difference. “___ minus ____ equals ____.”

Subtract fractions with unlike denominators.1234

5a

To subtract fractions, both fractions must have like denominators.

How did I/you find the least common denominator? How did I/you create equivalent fractions? How did I/you subtract fractions?

CFU

2

3

4

2: 2, 4, 6, 8

1 1

2 3 1.

3: 3, 6, 9, 121

2

1

3

6

6

3

3×

×

3

6

2

2

2

6

3 2

6 6

1

6

1

6

1 2

2 5 2.

2: 2, 4, 6, 8, 10 5: 5, 10, 15, 20

1

2

2

5

10

10

5

5×

×

5

10

2

2

4

10

5 4

10 10 1

10

1

10

3 1

4 12 3.

4: 4, 8, 12, 16 12: 12, 24, 36, 48

3

4

1

12

12

12

3

3×

×

9

12

1

1

1

12

9 1

12 12

8

12

2

3

2

3

4 1

8 6 4.

8: 8, 16, 24, 32 6: 6, 12, 18, 24

4

8

1

6

24

24

3

3×

×

12

24

4

4

4

24

12 4

24 24

8

24

1

3

1

3



Skill Development/Guided Practice (continued)

5. Sherry bought of a pound of milk chocolate and of a pound of white

chocolate. How much more milk chocolate than white chocolate does Sherry

have?

3

4

1

2

4: 4, 8, 12, 16 2: 2, 4, 6, 8

6. Tom bought of a pound of cauliflower and of a pound of celery.

How much more cauliflower than celery did he buy?

2

3

1

5

3

4

1

24

4

1

1× ×

3

4

2

2

2

4

3 2

4 4

1

4

3: 3, 6, 9, 12, 15 5: 5, 10, 15, 20

2

3

1

515

15

5

5× ×

10

15

3

3

3

15

10 3

15 15

7

15

1

4Sherry bought ____ of a pound more ______________ than _______________.milk chocolate white chocolate

7

15Tom bought ____ of a pound more __________ than ___________.cauliflower celery

How did I/you determine what the question is asking?How did I/you determine the math concept required?How did I/you determine the relevant information?How did I/you solve and interpret the problem?How did I/you check the reasonableness of the answer?

CFU

2

1

3

4

5

required = needed relevant = has to do with problemreasonableness = possible



There is of the pie left.

12

12

14

14

of the pie was left over after the party. Erick just ate of the pie. How much pie is left?

+ =

14

14+ =

1

Does anyone else have another reason why it is relevant to subtract fractions with unlike denominators? (Pair-Share) Why is it relevant to subtract fractions with unlike denominators? You may give me one of my reasons or one of your own. Which reason is more relevant to you? Why?

CFU

2

Relevance

Subtracting fractions will help you do well on tests.


12

12 + =

Sample Test Question:

53.

A

B

C

D

1 1

3 4

1

51

101

121

11

Subtracting fractions will help solve real-life problems.



2. Carmen bought of a pound of grapes and of a pound of nectarines.

How many more pounds of nectarines than grapes did Carmen buy?

What did you learn today about subtracting fractions with unlike denominators? (Pair-Share) Use words from the word bank.

Access Common Core

Summary Closure

Read the problem and identify fractions, if necessary. (circle)Find the least common denominator. Hint: Find the lowest shared multiple.Create equivalent fractions with like denominators. Hint: Use the least common denominator.

Subtract fractions. Hint: Subtract the numerators, keep the denominators the same.Reduce the difference, if possible.

Interpret the difference. “___ minus ____ equals ____.”


4

5a


Skill Closure

Which pair of fractions is ready to be subtracted? Explain your answer.

3 15 6

A 3 14 4

B

3 1

4 8 1. 4: 4, 8, 12, 16

8: 8, 16, 24, 32

3

4

1

88

8

2

2× ×

6

8

1

1

1

8

6 1

8 8

5

8

5

8

3

41

2

4: 4, 8, 12, 16 2: 2, 4, 6, 8

3

4

1

24

4

1

1× ×

3

4

2

2

2

4

3 2

4 4

1

41

4Carmen bought ____ of a pound more __________ than ___________.grapes nectarines

Word Bank

fractionslike/unlike

denominatorleast common denominatorequivalent



Independent Practice


6: 6, 12, 18, 24

5 2

6 3 1.

3: 3, 6, 9, 12

3 3

8 12 2.

3. The Smith family bought a pizza. Jason ate of the pizza and Jamie ate of the pizza. How much more pizza did Jason eat than Jamie?

5

6

2

3

6

6

1

1×

×

5

6

2

2

4

6

5 4

6 6

1

6

1

6

8: 8, 16, 24, 32 12: 12, 24, 36, 48

3

8

3

12

24

24

3

3×

×

9

24

2

2

6

24

9 6

24 24

3

24

1

8

1

8

2

71

4

7: 7, 14, 21, 28, 35 4: 4, 8, 12, 16, 20, 24, 28

2

7

1

428

28

4

4× ×

8

28

7

7

7

28

8 7

28 28

1

28

1

28_________ ate ____ of a pizza more than _________.JamieJason

Read the problem and identify fractions, if necessary. (circle)Find the least common denominator. Hint: Find the lowest shared multiple.Create equivalent fractions with like denominators. Hint: Use the least common denominator.

Subtract fractions. Hint: Subtract the numerators, keep the denominators the same.Reduce the difference, if possible.

Interpret the difference. “___ minus ____ equals ____.”


4

5a



Periodic Review 1

Access Common Core

12: 12, 24, 36

11 1

12 4 1.

4: 4, 8, 12, 1611

12

1

4

12

12

1

1×

×

11

12

3

3

3

12

11 3

12 12

8

12

2

3

2

3

3 4

6 12 2.

6: 6, 12, 18, 24, 32 12: 12, 24, 36, 48

3

6

4

12

12

12

2

2×

×

6

12

1

1

4

12

6 4

12 12

2

12

1

6

1

6

3. Geoff has of a pound of cashews and buys of a pound of pecans. How many more pounds of cashews does he have than pecans?

Geoff has ____ of a pound more ___________ than __________.

3

41

6

4: 4, 8, 12, 16 6: 6, 12, 18

3

4

1

612

12

3

3× ×

9

12

2

2

2

12

9 2

12 12

7

12

7

12

Abdul subtracted the fractions below. His teacher, Mrs. Treadwell, says that his answer is incorrect. Explain the mistake that Abdul made.

10 1

12 4

pecanscashews



Periodic Review 2

Access Common Core

6: 6, 12, 18, 24

4 3

6 8 1.

8: 8, 16, 24

9 1

10 4 2.

4

6

3

8

24

24

4

4×

×

16

24

3

3

9

24

16 9

24 24

7

24

7

24

10: 10, 20, 30, 40 4: 4, 8, 12, 16, 20

9

10

1

4

20

20

2

2×

×

18

20

5

5

5

20

18 5

20 20

13

20

13

20

Horatio added the fractions below. Some of his answers are incorrect. Circle all the incorrect answers and write the correct solutions.



Periodic Review 3

Access Common Core

12: 12, 24, 36

11 3

12 4 1.

4: 4, 8, 12, 16

3 3

5 10 2.

11

12

3

4

12

12

1

1×

×

11

12

3

3

9

12

11 9

12 12

2

12

1

6

1

6

5: 5, 10, 15, 2010: 10, 20, 30

3

5

3

10

10

10

2

2×

×

6

10

1

1

3

10

6 3

10 10

3

10

3

10

Choose Yes or No to show whether each choice is

equal to the difference of .

Yes No

Yes No

Yes No

Yes No



EDI – Cognitive, Teaching, and English Learner Strategies

Learning Objective: We will subtract fractions with unlike denominators.

Elaboration

Targeted Vocabulary

Academic identify, interpret

Content least common denominator, equivalent, difference

Support

Demonstration

VocabularyStrategy

Multiple-Meaning

Synonym identify, interpretDefinition least common denominator, equivalent, difference

Homophone

Internal Context Clue

Listen, Speak Similar Sounds

Write Writing

Read Tracked Reading

Comprehensible Input Cognates

Contextual Clues

Graphic Organizer

Contextualized Definitions

Pictures

Language Strategies

Cognitive Strategies Teaching Strategies

Content Access Strategies

5 th Grade Math Learning Objective: We will subtract fractions with unlike denominators. READY TO TEACH SM EDI ® Lessons ©2013 All rights reserved. EDI.

Documents

equivalent fractions

operations fractions

given fractions

difference of fractions

subtraction of fractions

benchmark fractions

pair of fractions

number sense of fractions