Eureka Math
3rd Grade
Module 1
Lesson 8
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!
Directions for customizing presentations are available on the next slide.
Customize this Slideshow
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 demonstrate the commutativity of Multiplication and practice related facts by skip-counting objects in array models.
Group Counting
Let’s count by twos to 20.
Whisper the numbers, then speak them.
Group Counting
Let’s count by twos to 20 again.
This time, hum the first number, and then speak it.
As you hum, think of the number.
Group Counting
Count by twos to 20 again.
This time, instead of humming, think of every other number
What did we just count by?
Group Counting
Let’s count by fours.
Count up Count Down
Group Counting
Let’s count by threes.
Count up Count Down
Commutative Multiplying
How many groups of twos do you see?
Commutative Multiplying
Write two different multiplication sentences for the array.
Commutative Multiplying
How many groups of fives do you see?
Commutative Multiplying
Write two different multiplication sentences for the array.
Commutative Multiplying
4 x 2 = 2 x ___
On your board, fill in the blank.
Commutative Multiplying
9 x 5 = 5 x ___
On your board, fill in the blank.
Commutative Multiplying
3 x 6 = 6 x ___
On your board, fill in the blank.
Application Problem
Children sit in 2 rows of 9 on the carpet for math time. Erin says, “We make 2 equal groups.” Vittesh says, “We make 9 equal groups.” Who is correct? Explain how you know using models, numbers, and words.
Rotate 90 Degrees
Turn your personal white board so that the long side is vertical.
Skip-count by threes 4 times and write each number.
Rotate 90 Degrees
Draw an array to match your count where number of rows represents the number of groups.
Discuss how many rows and columns you see.
Rotate 90 Degrees
Turn your board so that the long side is horizontal. How many rows and columns does it show?
What is the difference between the vertical and horizontal arrays?
Rotate 90 degrees
Did the total number of dots change?
So, the total and the factors stay the same, but the factors switch places.
Yesterday we learned a special name for that. It’s called...
Rotate 90 degrees
Use the commutative property to write two multiplication sentences for the array.
Rotate 90 Degrees
Practice with a partner!
Partner A gives skip counting directions. Partner B writes the count, draws an array, and writes the multiplication sentences. Then, partners switch roles.
Interpreting rows and columns in rotated arrays
Work with your partner to draw an array that shows 5 rows and 3 columns.
Interpreting rows and columns in rotated arrays
Write an equation to match your array where the first factors represents the number of rows. Don’t solve it yet.
Interpreting rows and columns in rotated arrays
5 x 3 = ___
I’m going to change the problem slightly. Listen carefully and rotate your array to match: 3 rows and 5 columns.
Interpreting rows and columns in rotated arrays
Write the equation to the new array. Let the first factor represent the number of rows. Don’t solve it yet.
Interpreting rows and columns in rotated arrays
3 x 5 = ___
Explain the difference between these problems to your partner.
Interpreting rows and columns in rotated arrays
When we rotated our array, we agreed the first factor would tell us the number of rows. What did that do to the order of factors?
Did the total change?
Interpreting rows and columns in rotated arrays
When we change the order of the factors, we are using the commutative property.
Solve each of your equations by skip-counting. Write each number as you say it.
Interpreting rows and columns in rotated arrays
Interpreting rows and columns in rotated arrays
Continue with the following possible examples:
Are these statements equal?
Use your array to discuss with your partner how you know.
Problem Set
Debrief
Exit Ticket