Eureka Math Module 2 Lesson 9

Eureka

Module 2 Lesson 9

LO: I am learning how to multiply using
partial products.

Success Criteria

● I can represent units using strip diagrams and area models.

● I can represent products using area models and standard

algorithms.

● I can connect area models and the distributive property to partial

products of the standard algorithm with and without renaming.

Fluency
Estimate Products

​In little green book
(L9 mod 2)

Multiply Mentally

9 x 10 = _____

9 x 99 =______

9 x 9 = 90 - __

What’s 9 x 9

9 x 100 = _____

15 x 10 = _____

9 x 100 =900 - _____

15 x 9 = 150 - _____

What’s 15 x9

​Do together

Multiply by Multiples of 100

31 x 100 = _____

Your Turn

3,100 x 2 = _____

31 x 200 = _____

31 x 100 x 2 = _____

Fill in the Blank

24 x 300

Fill in the Blank

34 x 200

Multiple Choice

31 x 200 =

• 620

• 6,200

• 6,100

• 6,300

Application Problem

Aneisha is setting up a play space for her new
puppy. She will be building a rectangular fence
around part of her yard that measures 29 feet by 12 feet. How many square feet of play space will her new puppy have? If you have time, solve in
more than one way.

Concept Development
Problem 1

21 x 5

Represent with a strip diagram

So you chose the factor 5 to be the unit. Can you imagine the area
in each unit?

​JOURNAL

Imagine that all 21 rows of boxes are stacked vertically.

There are so many units in this drawing. Let’s represent all of the boxes
using an area model.

1

20

5

What values could you put in the area model?

How are the area model and the strip diagram similar?

How are they different?

Can we turn this area model so that we count 5 groups of 21?

21

5

Problem 2

23 x 31

1 2 3

X 3 1

2 3

30

+ 6 9 0

7 1 3

23

690

23

(1 x 23) + (30 x 23) =

23 + 690 =

713

Problem 3

343 x 21

1 3 4 3

X 2 1

3 4 3

20

+6, 8 6 0

7, 2 0 3

343

6,860

343

(1 x 343) + (20 x 343) =

343 + 6,860 =

7,203

Problem Set

Debrief

Look at the area model in 1a and 1b. What is the same about
these two problems?

How could you help question 1 to help you solve question 2?

Does using a decimal value like 12.1 as the unit being counted
change the way you must think about the partial products?

Exit Ticket