Download Module 3 Lesson 7 - Peoria Public Schools

Math Module 3
Multi-Digit Multiplication and Division
Topic C: Multiplication of up to Four Digits by Single-Digit Numbers
Lesson 7: Use place value disks to represent two-digit by one-digit multiplication
4.OA.2 4.NBT.5 4.NBT.1
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We can do this!
Lesson 7
Target
You will use place value
disks to represent twodigit by one-digit
multiplication
Fluency
Practice
– Sprint
A
Take
your
mark!
Get set!
Think!
Fluency
Practice
– Sprint
B
Take
your
mark!
Get set!
Think!
Lesson 7
Fluency
Multiply Mentally
1 x 4 = ____
• Say the multiplication
sentence.
• 1 x 4 = 4.
20 x 4 = ____
• Say the multiplication
sentence.
• 20 x 4 = 80.
21
x
4
=
____
• Say the multiplication
sentence.
• 21 x 4 = 84.
4 x 4 = ____
• Say the multiplication
sentence.
• 4 x 4 = 16.
20 x 4 = ____
• Say the multiplication
sentence.
• 20 x 4 = 80.
24 x 4 = ____
• Say the multiplication
sentence.
• 24 x 4 = 96 .
Lesson 7
Fluency
Multiply Mentally
3 x 2 = ____
• Say the multiplication
sentence.
• 3 x 2 = 6.
40 x 2 = ____
• Say the multiplication
sentence.
• 40 x 2 = 80.
43
x
2
=
____
• Say the multiplication
sentence.
• 43 x 2 = 86.
2 x 3 = ____
• Say the multiplication
sentence.
• 2 x 3 = 6.
30 x 3 = ____
• Say the multiplication
sentence.
• 30 x 3 = 90.
32 x 3 = ____
• Say the multiplication
sentence.
• 32 x 3 = 96.
Application Problem
Lesson 7
The basketball team is selling tshirts for $9 each. On Monday,
they sell 4 t-shirts. On Tuesday,
they sell 5 times as many tshirts as on Monday. How much
money did the team earn
altogether on Monday and
Tuesday?
Lesson 7
Concept Development
Lesson 7
Problem 1: Represent 2 × 23 with disks, writing a matching equation and recording the partial
products vertically.
• Use your place value chart and draw disks to
represent 23.
• Draw disks on your place value chart to show
1 more group of 23. What is the total value in
the ones?
• 2 × 3 ones = 6 ones = 6.
• Write 2 × 3 ones under the ones column.
• Let’s record 2 × 23 vertically.
• We record the total number for the
ones below, just like in addition.
==
==
===
===
2 x 3 ones
23
x2
6 2 x 3 ones
6 ones
Concept Development
Lesson 7
Problem 1: Represent 2 × 23 with disks, writing a matching equation and recording the partial
products vertically.
Notice that when we
addWhat
the values
that we
• Let’s look at the tens.
is the total
value in the tens? wrote below the line
• 2 × 2 tens = 4 tensthat
= 40they add to 46, the
• Write 2 × 2 tens under theproduct!
tens column.
• Let’s represent our answer in the
equation. We write 40 to represent
the value of the tens.
• What is the total value represented
by the disks?
==
==
===
===
2 x 2 tens 2 x 3 ones
4 tens + 6 ones = 46
23
x2
6 2 x 3 ones
+ 40 2 x 2 tens
46
Concept Development
Problem 1: Represent 3 × 23 with disks, writing a matching equation and recording the partial
Lesson 7
products vertically.
• Use your place value chart and draw disks to
represent 23.
• Draw disks on your place value chart to show
2 more groups of 23. What is the total value in
the ones?
• 3 × 3 ones = 9 ones = 9.
• Write 3 × 3 ones under the ones column.
• Let’s record 3 × 23 vertically.
• We record the total number for the
ones below, just like in addition.
==
==
==
===
===
===
3 x 3 ones
23
x3
9 3 x 3 ones
9 ones
Concept Development
Problem 1: Represent 3 × 23 with disks, writing a matching equation and recording the partial
Lesson 7
products vertically.
• Let’s look at the tens. What is the total
value in the tens?
• 3 × 2 tens = 6 tens = 60
• Write 3 × 2 tens under the tens column.
• Let’s represent our answer in the
equation. We write 60 to represent
the value of the tens.
• What is the total value represented
by the disks?
==
==
==
===
===
===
3 x 2 tens 3 x 3 ones
6 tens + 9 ones = 69
23
x3
9 3 x 3 ones
+ 60 3 x 2 tens
69
Concept Development
Lesson 7
Problem 2: Model and solve 4 × 54.
•
•
•
•
Draw disks to represent 54 on your place value chart.
What is 54 in unit form?
5 tens 4 ones.
Draw 3 more groups of 54 on your chart and then write
the expression 4 × 54 vertically on your board.
• What is the value of the
ones now?
• 4 × 4 ones = 16 ones.
• Record the value of the
ones.
Hundreds
Tens
ones
54
x4
16 ones
Concept Development
Lesson 7
Problem 2: Model and solve 4 × 54.
•
•
•
•
What is the value of the tens?
4 × 5 tens = 20 tens.
Record the value of the tens.
Add up the partial
products you
recorded. What is the Hundreds
sum?
• 20 tens + 16 ones =
216
• Let’s confirm that on
our place value chart.
Tens
ones
54
x4
20 tens
16 ones
Concept Development
Lesson 7
Problem 2: Model and solve 4 × 54.
•
•
•
•
Can we change to larger units?
We can change 10 ones for 1 ten and 10 tens for 1 hundred twice.
Show me on your board.
What value is represented on the place value chart?
Hundreds
Tens
ones
54
x4
20 tens
16 ones
2 hundreds + 1 ten + 6 ones = 216
Concept Development
•
•
•
•
Lesson 7
Problem 2: Model and solve 5 × 52.
Draw disks to represent 52 on your place value chart.
What is 52 in unit form?
5 tens 2 ones.
Draw 4 more groups of 52 on your chart and then write
the expression 5 × 52 vertically on your board.
Hundreds
Tens
ones
• What is the value of
the ones now?
• 5 × 2 ones = 10 ones.
• Record the value of the
ones.
10 ones
52
x5
Concept Development
Lesson 7
Problem 2: Model and solve 5 × 52.
•
•
•
•
What is the value of the tens?
5 × 5 tens = 25 tens.
Record the value of the tens.
Add up the partial
products you recorded. Hundreds
What is the sum?
• 25 tens + 10 ones = 260
• Let’s confirm that on
our place value chart.
Tens
ones
52
x5
25 tens
10 ones
Concept Development
Lesson 7
Problem 2: Model and solve 5 × 52.
•
•
•
•
Can we change to larger units?
We can change 10 ones for 1 ten and 10 tens for 1 hundred twice.
Show me on your board.
What value is represented on the place value chart?
Hundreds
Tens
ones
52
x5
10=ones
tens + 0 ones
2 hundreds + 625tens
260
Problem Set
10 Minutes
Problem Set
10 Minutes
• What pattern do you notice in
the answers to Problems 1(a),
1(b), 1(c), and 1(d)?
• Describe the renaming you had to do when
solving Problem 2(a). How is it different
from the renaming you had to do when
solving Problem 2(b)?
Debrief
Lesson Objective:
Use place value
disks to represent
two-digit by onedigit multiplication
• Why did some of the problems require you to use
a hundreds column in the place value chart, but
others did not?
• When you start solving one of these problems, is
there a way to tell if you are going to need to
change 10 tens to 1 hundred or 10 ones to 1 ten?
• How did the Application Problem connect to
today’s lesson? If we found the total number of
shirts sold first (24) and then multiplied to find the
total amount of money, what would our
multiplication problem have been? (24 × 9.)
• What do the partial products for 24 × 9 represent
in the context of the word problem?
• Talk to your partner about which method you
prefer: writing the partial products or using a
place value chart with disks? Is one of these
methods easier for you to understand? Does one
of them help you solve the problem faster?
Exit Ticket
Lesson 1