Welcome Second Grade

Commutative Property- Day 1

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Today we will...• 2.8.2.A: Use the concept of equality

and concrete objects to demonstrate understanding of the commutative and associative properties.

• Essential Question:– How do I identify the Commutative

Property, and how does this property help me with my math?

Math Giggles

New Math WordsThis week, we will be looking at

the commutative property of addition and multiplication.

What is this? Let’s take a closer look…

Commutative Property

The commutative property states that you can add numbers in any order and get the same sum. You can also multiply two numbers in

any order and get the same product.

Let’s Take a Closer Look

Let’s Take a Closer Look

5 + 4= 9

4 + 5= 9We can show the commutative

property using two number sentences:

5 +4=94+5=9

You can also show it as one

number sentence:

5 + 4= 4 + 5

Circle the model that shows the commutative property of addition.

3 + 5 = 8

4 + 4 = 8

5 + 3 = 83 + 3 = 6

Let’s look at this example..

Complete the remainder of this number sentence:

3 + 4 = +

Your Turn5 + 2 = ___+___

5 + 2 = 7 __ + __ = 7

8 + 3= ___+___ 8 + 3 = 11 __ + __ = 11

4 + 5 = ___+___

4 + 5 = 9 __ + __ = 9

6 + 3 = ___+___

6 + 3 = 9 __ + __ = 9

Now, Let’s Look at Multiplication...

This array shows a multiplication sentence.

3 x =

Look at it another way.

Now, the array has been turned on its side. The sentence now looks a little different

5 x =

We just found that...

AND

3 x 5 = 15 5 x 3 = 15

You can also see the commutative property in

multiplication. This property can be shown using the two number sentences above or as one number sentence:

3 x 5 = 5 x 3

Let’s look at this example...

Complete the remainder of this number sentence:

2 x 4 = x

Your Turn

5 x 2 = ___x___ 5 x 2 = 10 __ x __ = 10

2 x 3= ___x___ 2 x 3 = 6 __ x __ = 6

4 x 5 = ___x___ 4 x 5 = 20 __ x __ = 20

6 x 3 = ___x___ 6 x 3 = 18 __ x __ = 18

How can this property help us?

You know that you can add or multiply numbers in any order. You can use this idea

to find answers faster.

3 + 22 = ____

To find the answer faster, we can start with 22 and add 3 to get 25.

22 + 3 = 25

Adding 3 AddendsWe can also use the commutative property when adding 3 addends together. Look at the example

below.

39 + 53 + 1 = ?

We can switch 53 and 1 to add 39 and 1 together first.

40 + 53 = _____40 is a friendly

number because it ends in 0.

Your Turn!Circle which two numbers would be easier to add

first.

Circles

Your Turn!

What is the sum of 18 + 2?

Your Turn!

What is the sum of 18 + 2?

20 + 25 =

Let’s Try Another One

28 + 34 + 2 = ?

Circles

Let’s Try Another One

15 + 23 + 5 = ?

Circles

Awesome Work!!• Now it’s time for you to try some on your

own.

• I will push out the Compass website to you so that you can complete this week’s pretest.

• Don’t forget to log-in a complete your lessons this week if you have a learning path!

How to take the pre-test...• Log in to Compass with your username

and password.

• Click on Math Assignments.

• Choose the folder: M2.A.2.8.2_Pre

• Complete the pre-test. When you finish, make sure that you click and then “turn-in” to turn in your test.