Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers - PC\|MAC

[Pages:10]Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

Lesson: 5.1.4 ? Supplement Multiplying Fractions and Mixed Numbers

Teacher Lesson Plan

CC Standards

This lesson is a prerequisite to objective 6.NS.1 which is dividing fractions. In order to divide fractions, students must be

able to multiply fractions. Lesson 5.1.1 ? 5.1.3 focused on multiplying fractions using visual models. This lesson will teach the traditional method. In 5th grade students did learn to multiply fractions by fractions and fractions by whole

numbers. Their exposure to cross canceling and multiplying mixed numbers will be limited.

Prerequisite to 6.NS.1 Interpret and compute quotients of fractions, and solve word problems involving division of fractions by fractions, e.g., by using visual fraction models and equations to represent the problem.

Objective Students will learn the traditional method of multiplying fractions and mixed numbers.

Mathematical Practices #1 Make sense of problems and persevere in solving them #8 Look for and express regularity in repeated reasoning

Teacher Input Bellwork: Homework: Introduction:

Lesson:

Review bellwork. Review previous night's homework. The PowerPoint "Multiplying Fractions" is a real-world multiplication problem dealing with ones weight during super gravity on a roller coaster. The purpose of the PowerPoint is to link multiplication of fractions to the real world and to hook the students into the lesson using an interesting topic. Be sure to look at the notes section on each slide of the PowerPoint for additional information and answers. After you introduce the lesson via the above PowerPoint, scroll down to page 2 of this document to begin your instruction. Review steps to multiple mixed numbers. Then work through the guided practice problems together whole group. Students should then try the you-try problems independently before moving on to the classwork. Try to get the students to cross cancel even though it may be a challenge at first. It is a skill that 7th and 8th grade teaches wish they had coming in to them. They will learn to love it.

Practice Classwork: Homework: Extra Practice:

Page 3 Page 5 Page 4

Closure

Everyone.... On a piece of scratch paper, take your own weight and calculate how heavy you would feel when

"Supergravity" takes

place

on the Phantoms Revenge.

Remember,

you

would

feel

3

1 2

times your weight!

Sample response:

3

x 120 lbs =

x

= 420 lbs

What are the steps you used to find Supergravity? Step 1: Convert mixed number to improper fraction. Step 2: Cross cancelled. Step 3: Multiplied numerators and denominators. Step 4: Simplified my answer.

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

Student Notes

Section 1: Vocabulary

Proper Fraction ? A fraction that is less than one with the numerator being less than the denominator. ?

Improper Fraction ? A fraction in which the numerator is greater than the denominator. 5/4

Mixed Number ? A number consisting of a whole number and a proper fraction. 4?

Cross Cancel ?

Instead of reducing the fraction at the end of the problem, you can crosscancel before you multiply. Cross-canceling means that when multiplying fractions you can reduce the numerator of one fraction with the denominator of another. Basically, cross canceling is simplifying before you multiply!

Section 2: Steps for Multiplying Fractions and Mixed Numbers

Example:

Multiply

62

3

?

15 16

Step 1 Convert mixed numbers to improper fractions.

20 ? 15

3

16

Step 2 Cross cancel when possible.

5

5

20

15

3

16

1

4

Step 3 Multiply the numerators. Multiply the denominators.

5 1

?

5 25 4= 4

Step 4 Simplify.

25 4 =

Section 3: Teacher Guided Practice Find the products. Be sure to cross cancel when possible! Remember, when cross canceling, anything on the top can be cross canceled with anything on the bottom!

1) 4 4 ? 3 3

5

4

2) 21 ? 1 =

5

7

3)

14 ?

23

8

=

4) 24 ? 4 =

32

7

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

You-Try Independent Practice

Find the products. Show your work and be sure to cross cancel when possible! Remember, when cross canceling, anything on the top can be cross canceled with anything on the bottom!

1) 7 ? 4 =

21

9

2) 5 ? 10 =

7

15

3) 4 5 ? 3 3

10

4

4) 1 5 ? 3 2

7

6

5) 3 2 ? 5 3

6

5

Name_______________________ Date__________ Period: ____

Classwork

Multiply. Write answer in simplest form. Practice cross cancelling when possible!

1) 2 ? 1 3 4

2) 3 ? 1

7 2

3) 1 ? 3

3 5

4) 1 1 ? 3

9 5

5) 1 ? 6 2 7

6) 3 ? 4

8

7) 7 ? 5

10 7

8) 6 ? 11

12

9) 4 ? 3 9

10)1 ? 1

4 4

11)1 1 ? 6

2

12) 1 ? 2 2

2

3

13) 3 ? 1 2

4

3

14) 3 1 ? 2 1

3

2

15) 4 1 ? 1

5 7

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

Name_______________________ Date__________ Period: ____

Extra Practice

Solve the fraction problem and reduce the answer to simplest form. Be sure to show your work and practice cross canceling whenever possible.

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

Name_______________________ Date__________ Period: ____

Homework

Solve the fraction problem and reduce the answer to simplest form. Be sure to show your work and practice cross canceling whenever possible.

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

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Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

Student Notes

Section 1: Vocabulary

Answer Key

Proper Fraction ? A fraction that is less than one with the numerator being less than the denominator. ?

Improper Fraction ? A fraction in which the numerator is greater than the denominator. 5/4

Mixed Number ? A number consisting of a whole number and a proper fraction. 4?

Cross Cancel ?

Instead of reducing the fraction at the end of the problem, you can crosscancel before you multiply. Cross-canceling means that when multiplying fractions you can reduce the numerator of one fraction with the denominator of another. Basically, cross canceling is simplifying before you multiply!

Section 2: Steps for Multiplying Fractions and Mixed Numbers

Example:

Multiply

62

3

?

15 16

Step 1 Convert mixed numbers to improper fractions.

20 ? 15

3

16

Step 2 Cross cancel when possible.

5

5

20

15

3

16

1

4

Step 3 Multiply the numerators. Multiply the denominators.

5 1

?

5 25 4= 4

Step 4 Simplify.

25 4 =

Section 3: Teacher Guided Practice Find the products. Be sure to cross cancel when possible! Remember, when cross canceling, anything on the top can be cross canceled with anything on the bottom!

1) 4 4 ? 3 3 =

5

4

2) 21 ? 1 =

5

7

3) 14 ? 2 3 =

8

4) 24 ? 4 =

32

7

7|Page

Lesson 5.1.4 ? Multiplying Fractions and Mixed Numbers

You-Try Independent Practice

Find the products. Show your work and be sure to cross cancel when possible! Remember, when cross canceling, anything on the top can be cross cancelled with anything on the bottom!

1) 7 ? 4 =

21

9

2) 5 ? 10 =

7

15

3) 4 5 ? 3 3 =

10

4

4) 1 5 ? 3 2 =

7

6

5) 3 2 ? 5 3 =

6

5

Name_______________________ Date__________ Period: ____

Classwork

Answer Key

Multiply. Write answer in simplest form. Practice cross cancelling when possible!

1) 2 ? 1 3 4

2) 3 ? 1

7 2

3) 1 ? 3

3 5

4) 1 1 ? 3

9 5

5) 1 ? 6 2 7

6) 3 ? 4

8

7) 7 ? 5

10 7

8) 6 ? 11

12

9) 4 ? 3

9

10)1 ? 1

4 4

11)1 1 ? 6

2

12) 1 ? 2 2

2

3

13) 3 ? 1 2

4

3

14) 3 1 ? 2 1

3

2

15) 4 1 ? 1

5 7

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