Lesson 4.1
Name
Multiply with 2 and 4
Operations and Algebraic
Thinking—3.OA.A.3
Also 3.OA.A.1, 3.OA.C.7
MATHEMATICAL PRACTICES
MP1, MP4, MP5, MP7
Essential Question How can you multiply with 2 and 4?
Hands
On
Unlock
Unlock the
the Problem
Problem
Two students are in a play. Each
of the students has 3 costumes.
How many costumes do they
have in all?
Multiplying when there are two
equal groups is like adding doubles.
• What does the word “each” tell you?
• How can you find the number of costumes the
2 students have?
Find 2 × 3.
3+3
6
2
×
3
=
6
←
2 groups of 3
RECORD
←
Draw counters to show the
costumes.
THINK
←
MODEL
how
how many how
many
in each
many
groups group
in all
So, the 2 students have _ costumes in all.
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Try This!
2×1=1+1=2
2×_=6+_=_
2×2=2+2=4
2×_=7+_=_
2×_=3+_=6
2×_=8+_=_
2×_=4+_=8
2×_=9+_=_
Math
MATHEMATICAL PRACTICES
Talk
2×_=5+_=_
2
Reason Abstractly What
do you notice about
the product when you
multiply by 2?
Chapter 4
191
Count by 2s.
When there are 2 in each group, you can count
by 2s to find how many there are in all.
There are 4 students with 2 costumes each.
How many costumes do they have in all?
Skip count by drawing the jumps on the number line.
0
1
2
3
4
5
6
7
8 9 10
So, the 4 students have ___ in all.
• How can you decide whether to count by 2s or double?
Example Use doubles to find 4 × 5.
When you multiply with 4, you can multiply
with 2 and then double the product.
4×5
MULTIPLY WITH 2
DOUBLE THE PRODUCT
2 × 5 = 10
10 + 10 = 20
So, 4 × 5 = _.
MATH
M
BOARD
B
1. Double 2 × 7 to find 4 × 7.
Multiply with 2. 2 × 7 = _
Double the product. 14 + 14 = _
So, 4 × 7 = _.
192
Math
Talk
MATHEMATICAL PRACTICES 7
Identify Relationships
Explain how knowing
the product for 2 × 8
helps you find the
product for 4 × 8.
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Share
hhow
Share and
and Show
Sh
Name
Write a multiplication sentence for the model.
2.
3.
_×_=_
_×_=_
Find the product.
4.
5.
7.
8
×4
_
ˇ 8.
5
×2
_
Find the product. Use your MathBoard.
9.
10
10.
2
11.
4
× 4
×9
×6
_
_
_
12.
7
×2
_
13.
2
×0
_
14.
17.
10
×
2
_
18.
4
×
5
_
6
×2
_
6.
9
×4
_
2
×7
_
On
On Your
Your Own
Own
15.
4
×
3
_
16.
2
×
8
_
4
×
4
_
Look for Structure Algebra Complete the table
for the factors 2 and 4.
MATHEMATICAL
PRACTICE
7
1
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3
19.
2
20.
4
MATHEMATICAL
PRACTICE
2
3
4
5
6
7
8
9
10
Reason Quantitatively Algebra Write the unknown number.
21. 4 × 8 = 16 + _
24.
2
22. 20 = 2 × _
23. 8 × 2 = 10 + _
Lindsey, Louis, Sally, and Matt each
brought 5 guests to the school play. How many guests
were at the school play? Explain.
SMARTER
Chapter 4 • Lesson 1 193
MATHEMATICAL PRACTICES
COMMUNICA5&t1&34E7&3&tCONSTRUCT ARGUMENTS
Unlock
Unlock the
the Problem
Problem
25.
Play Tickets
DEEPER
Ms. Peterson’s class sold
tickets for the class play. How many
tickets in all did Brandon and
Haylie sell?
a. What do you need to find?
Brandon
Haylie
Elizabeth
Key: Each
= 2 tickets sold.
–b. Why should you multiply to find the number of tickets
shown? Explain.–
c. Show the steps you used to solve
the problem.
d. Complete the sentences.
Brandon sold _ tickets. Haylie sold
WRITE
MBrandon
t Showand
YourHaylie
Work
_ tickets.
So,Math
sold _ tickets.
26.
Analyze Suppose Sam sold 20 tickets to
the school play. How many tickets should be on the
picture graph above to show his sales? Explain.
27.
Alex exchanges some dollar bills for quarters
at the bank. He receives 4 quarters for each dollar bill. Select the
numbers of quarters that Alex could receive. Mark all that apply.
SMARTER
A 16
D 32
B 18
E 50
C 24
194
1
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MATHEMATICAL
PRACTICE
Practice and Homework
Lesson 4.1
Name
Multiply with 2 and 4
COMMON CORE STANDARD—3.OA.A.3
Represent and solve problems involving
multiplication and division.
Write a multiplication sentence for the model.
1.
2.
Think: There are 2 groups of
5 counters.
2 ×_
5 =_
10
_
_×_=_
Find the product.
3.
2
×
_6
4.
4
×
_8
5.
2
×
_3
6.
4
×
_6
Problem
Problem Solving
Solving
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7. On Monday, Steven read 9 pages
9.
8. Courtney’s school is having a family
of his new book. To finish the first
chapter on Tuesday, he needs to read
double the number of pages he read
on Monday. How many pages does he
need to read on Tuesday?
game night. Each table has 4 players.
There are 7 tables in all. How many
players are at the game night?
_______
_______
WRITE
Math Explain how you can use doubles when
multiplying with 4 to find 4 × 8.
Chapter 4
195
Lesson Check (3.OA.A.3)
1. What multiplication sentence matches
2. Find the product.
the model?
2
×
8
_
Spiral Review (3.NBT.A.2, 3.MD.B.3)
3. Sean made a picture graph to show his
friends’ favorite colors.
This is the key for the graph.
Each
= 2 friends.
How many friends does
stand for?
4. The table shows the lengths of
some walking trails.
Walking Trails
Name
Mountain Trail
Lake Trail
Harmony Trail
Length (in feet)
844
792
528
How many feet longer is Mountain
Trail than Harmony Trail?
527
+
154
__
6. A bar graph shows that sports books
received 9 votes. If the scale is 0 to
20 by twos, where should the bar
end for the sports books?
FOR MORE PRACTICE
GO TO THE
196
Personal Math Trainer
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5. Find the sum.