Eureka Math
5th Grade
Module 1
Lesson 12
At the request of elementary teachers, a team of Bethel & Sumner educators met as a committee to create Eureka slideshow presentations. These presentations are not meant as a script, nor are they required to be used. Please customize as needed. Thank you to the many educators who contributed to this project!
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Reflecting your Teaching Style and Learning Needs of Your Students
Screen A
“pop-out”
Screen B
Icons
Read, Draw, Write
Learning Target
Think Pair Share
Individual
Partner
Whole Class
Small Group Time
Small Group
Personal White Board
Problem Set
Manipulatives Needed
Fluency
I can multiply decimals by whole numbers and use estimation skills to determine the reasonableness of my answer.
SPRINT
Adding Decimals
(9 minutes)
Find the Product
Write and solve the multiplication sentence for 4 X 2 ones =
Repeat for the following multiplication sentences:
4 X 2 tenths =
4 X 2 hundredths =
5 X 3 ones =
5 X 3 tenths =
Find the Product
Write and solve the following multiplication sentences:
3 X 2 tenths =
3 X 3 hundredths =
3 X 23 hundredths =
2 X 14 hundredths =
Application Problem
Patty buys 7 juice boxes a month for lunch. If one juice box costs $2.79, how much money does Patty spend on juice each month? Use an area model to solve.
Extension: How much will Patty spend on juice in 10 months? In 12 months?
Multiplying Decimals
Use an Area Model to solve 31 X 4
| |
Multiplying Decimals
Use an Area Model to solve 31 X 4
12 tens | 4 ones |
3 tens + 1 one
4
120 + 4 = 124
Multiplying Decimals
Use an Area Model to solve 3.1 X 4
| |
Multiplying Decimals
3 ones + 1 tenth
4
12 + 0.4 = 12.4
Use an Area Model to solve 31 X 4
12 ones | 4 tenths |
Multiplying Decimals
Use an Area Model to solve .31 X 4
| |
Multiplying Decimals
3 tenths + 1 hundredth
4
1.2 + 0.04 = 1.24
Use an Area Model to solve .31 X 4
12 tenths | 4 hundredths |
Multiplying Decimals
Look at the products of the last 3 problems:
124 12.4 1.24
What do you see?
Do these numbers have the same value?
Can you explain a multiplying strategy that would let me multiply first and then put the decimal in after?
Multiplying Decimals
5.1 X 6 =
What is the smallest unit being multiplied?
How can we turn 5.1 into tenths?
What would our new multiplication problem be if we
write 5.1 as tenths?
Multiplying Decimals
5.1 X 6 = 51 tenths X 6
Solve the problem vertically:
5 1 tenths
X 6
306 Is 306 a reasonable answer for 5.1 X 6?
What numbers can you use to estimate the answer?
Multiplying Decimals
5.1 X 6 = 51 tenths X 6 = 306 tenths
5 1 tenths
X 6
306 tenths
If I use 5 X 6 = 30 to help me place the decimal, where
should I put the decimal?
So...does 306 tenths = 30.6?
Multiplying Decimals
11.4 X 4 =
What is the smallest unit we are multiplying?
How can I convert 11.4 into tenths? What power of 10 do I use to convert 11.4 to tenths?
Multiplying Decimals
11.4 X 4 =
What power of 10 do I use to convert 11.4 to tenths?
10 is the same as multiplying by 10, so 11.4 X 10 would give us 114 tenths.
1 1 4 tenths
X 4
1
Multiplying Decimals
1 1 4 tenths
X 4
4 5 6
Is 456 a reasonable answer for 11.4 X 4
What numbers would we use to estimate the product?
What would the final product be?
Multiplying Decimals
3.12 X 4 =
3 1 2 hundredths
X 4
1 2 4 8 hundredths
Which of these answers is the most reasonable?
1248 1.248 12.48 124.8
Explain your thinking to your partner.
Confirm your thinking using an area model.
Multiplying Decimals
3.42 X 6 =
3 4 2 hundredths
X 6
2 0 5 2 hundredths
Which of these answers is the most reasonable?
2052 2.052 20.52 205.2
Explain your thinking to your partner.
Confirm your thinking using an area model.
Multiplying Decimals
0.733 X 4 =
7 3 3 thousandths
X 4
Which of these answers is the most reasonable?
2.932 29.32 293.2 2932
Explain your thinking to your partner.
Multiplying Decimals
10.733 X 4 =
Can you convert 10.733 to thousandths?
Multiply vertically.
Multiplying Decimals
10.733 X 4 =
1 0 7 3 3 thousandths
X 4
4 2 9 3 2 thousandths
Which of these answers is the most reasonable?
.42932 4.2932 42.932 429.32
Explain your thinking to your partner.
Multiplying Decimals
5.733 X 4 =
Can you convert 5.733 to thousandths?
Multiply vertically.
Multiplying Decimals
10.733 X 4 =
5 7 3 3 thousandths
X 4
2 2 9 3 2 thousandths
Which of these answers is the most reasonable?
2.2932 22.932 229.32 2293.2
Explain your thinking to your partner.
Problem Set
Debrief
How can whole number multiplication help you with decimal multiplication?
How does the area model help you place the decimal correctly?
How does estimation help you place the decimal correctly?
Exit Ticket