Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers
Teacher Lesson Plan
Lesson:
5.1.4 – Supplement
Multiplying Fractions and Mixed Numbers
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:
Practice
Classwork:
Homework:
Extra Practice:
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.
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
1
“Supergravity” takes place on the Phantoms Revenge. Remember, you would feel 3 2 times your weight!
Sample response: 3
𝟏
𝟐
x 120 lbs =
𝟕
𝟐
x
𝟏𝟐𝟎
𝟏
= 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.
1|Page
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. 4½
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
Step 1
Convert mixed numbers
to improper fractions.
20
3
×
2
15
63 ×
16
Step 2
Cross cancel when
possible.
5
5
Step 3
Multiply the numerators.
Multiply the denominators.
15
20
15
5
16
3
16
1
1
4
×
5
4
=
Step 4
Simplify.
25
25
4
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
2)
4
5
21
5
× 3
×
1
7
3) 14 • 2
4)
24
32
×
3
4
=
3
=
8
4
7
=
2|Page
¾
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)
2)
7
21
5
7
4
×
×
9
10
15
=
=
5
3
3) 4 10 × 3 4
5
2
2
3
4) 1 7 × 3 6
5) 3 6 × 5 5
Name_______________________ Date__________
Period: ____
Classwork
Multiply. Write answer in simplest form. Practice cross cancelling when possible!
1)
5)
9)
2
3
1
2
4
9
3
×
1
×
6
2)
4
6)
7
× 3
3
7
3
8
×
2
1
1
4
4
14) 3
3)
2
× 4
10) ×
13) 4 × 1 3
1
1
3
×2
7)
1
7
1
2
1
2
5
7
× 6
1
1
5
7
15) 4 ×
1
3
9
5
4) 1 ×
5
×
10
11) 1
3
×
3
8) 6 ×
11
12
1
2
2
3
12) × 2
3|Page
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.
4|Page
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.
5|Page
Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers
6|Page
Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers
Student Notes
Answer Key
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. 4½
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
Step 1
Convert mixed numbers
to improper fractions.
20
3
×
2
15
63 ×
16
Step 2
Cross cancel when
possible.
5
5
Step 3
Multiply the numerators.
Multiply the denominators.
15
20
15
5
16
3
16
1
1
4
×
5
4
=
Step 4
Simplify.
25
25
4
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
2)
4
5
21
5
3
× 3 = 𝟏𝟖
4
×
1
7
3) 14 • 2
3
24
4
4)
32
×
8
7
=
𝟑
𝟓
= 𝟑𝟑
=
𝟏
𝟒
𝟑
𝟕
7|Page
¾
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)
2)
7
21
5
7
4
×
×
9
10
15
𝟒
=
𝟐𝟕
𝟏𝟎
=
5
𝟐𝟏
3
𝟕
3) 4 10 × 3 4 = 𝟏𝟔 𝟖
5
2
2
3
𝟓
4) 1 7 × 3 6 = 𝟓 𝟕
𝟐
5) 3 6 × 5 5 = 𝟏𝟖 𝟑
Name_______________________ Date__________
Period: ____
Classwork
Answer Key
Multiply. Write answer in simplest form. Practice cross cancelling when possible!
1)
5)
9)
2
3
1
2
4
9
3
×
1
𝟏
4
𝟔
×
6
𝟑
7
𝟕
× 3
𝟏
2
2)
6)
𝟏
𝟑
𝟏
13) 4 × 1 3 𝟏 𝟒
3
7
3
8
×
1
𝟑
2
𝟏𝟒
× 4
𝟏
𝟏
1
𝟏
4
4
𝟏𝟔
14) 3
1
3
×2
1
2
7)
𝟐
1
10) ×
3)
1
3
7
𝟏
𝟑
3
𝟏
5
𝟓
×
10
11) 1
𝟖
×
1
2
5
𝟏
7
𝟐
× 6 𝟗
1
1
𝟑
5
7
𝟓
15) 4 ×
4) 1
1
9
8) 6 ×
12)
1
2
×
3
𝟐
5
𝟑
11
12
× 2
2
3
𝟓
𝟏
𝟏
𝟏
𝟐
𝟑
8|Page
Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers
Name_______________________ Date__________
Period: ____
Extra Practice
Answer Key
Solve the fraction problem and reduce the answer to simplest form. Be sure to show your
work and practice cross canceling whenever possible.
)
9|Page
Lesson 5.1.4 – Multiplying Fractions and Mixed Numbers
Name_______________________ Date__________
Period: ____
Homework
Answer Key
Solve the fraction problem and reduce the answer to simplest form. Be sure to show your
work and practice cross canceling whenever possible.
)
10 | P a g e