Chapter 1

Getting ready for Addition and Subtraction concepts

PowerPoint by Susie Mumper3rd Grade HES2011

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• Vocabulary• Lesson 1.2• Lesson 1.4• Lesson 1.6

• Lesson 1.1• Lesson 1.3• Lesson 1.5

Lesson 1.6 objective – To use the problem solving skill choose the operation.

• Let’s chill out while we practice some math.• Time for some practice. Turn to p. 13 and we

will do numbers 1-4.

Math task

1. Math book p. 13 numbers 5-7 all.2. In your math journal answer this question:

Kevin has 56 stamps. Jill has 38 stamps. Write one addition and one subtraction problem using this information.– Remember you need to restate the question in

your answer , write in complete sentences and show your work.

3. Math game from the black box

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Lesson 1.5 objective – To subtract 2-digit numbers with and without regrouping.

• Khan academy subtraction 2• Now let’s practice. Turn in your math book to

p. 10 and we will do numbers 2-6 together.

Math task

1. Math book p. 11 numbers 7-37 odd2. In your math journal answer this question:

How does the inverse operation help you in subtraction?– Remember you need to restate the question in

your answer , write in complete sentences and show your work.

3. Math game from the black box

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Lesson 1.4 objective – To add 2 – digit numbers with and without regrouping.

• http://www.khanacademy.org/video/addition-2?playlist=Arithmetic

Let’s practice

• Turn in your math book to p. 9 and let’s do 2-6 together.

Math task

1. Math book p. 9 numbers 7-29 odd2. Answer this question in your math journal:

How would you add 54 and 28?3. Math game from the black box

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Lesson 1.3 objective – To use properties of addition

• What is the order property of addition?– You can add two or more numbers in any order and get the same

sum.– 6 + 7 = 13 or 7 + 6 =13

• What is the identity property of addition?– When you add zero to a number, the sum is that number.– 2 + 0 = 2 or 34 + 0 = 34 or 259 + 0 = 259

• What is the grouping property of addition? – You can group addends in different ways and still get the same

sum.– (9 + 1) + 4 = 14 or 9 + (1 + 4) = 14

Let’s practice together

• Turn in your math book to p. 7 and let’s do numbers 2-4 together.

Math task

1. Math book p. 7 numbers 5 – 21 odd.2. In your journal write a number sentence to

go with each of the addition properties listed on p. 6 in your math book.

3. Math game from the black box.

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Lesson 1.2 objective – To solve number sentences for missing addends.

• Today we are going to learn about missing addends.

• http://www.harcourtschool.com/activity/show_me/e453.htm

• http://teams.lacoe.edu/documentation/classrooms/linda/algebra/activities/hunt/hunt.html

Now let’s practice together

• Open your math book to p. 5 and let’s do 2-5 together.

Math task

1. MB p. 5 numbers 6-28 even.2. Find this missing addends and write them in

your journal:– 5 + ___= 12– ___ + 8 = 10– 9 + ___ = 15

3. Math game from the black box

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fact family

A fact family is a set of related addition and subtraction number sentences that use the same numbers.

4 + 7 = 1111 – 4 = 7

inverse operations

Inverse operations are operations that undo each other, such as addition and subtraction. They are opposites.

Order Property of Addition

The order property of addition states that when you add two numbers in any order, you get the same sum.

7 + 6 = 13 and 6 + 7 = 13

Identity Property of Addition

The identity property of addition states that when you add zero to a number, the sum does not change

12 + 0 = 12

Grouping Property of Addition

The grouping property of addition states that when you add three or more addends in different ways, the sum stays the same.

(9 + 1) + 4 = 9 + (1 + 4)10 + 4 = 9 + 5

14 = 14

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Lesson 1.1 Objective – To identify and write related addition and subtraction facts

The pictograph shows some of the animals on Brittany's farm

Animals on Brittany’s farm

Chickens

Cows

Ducks

Sheep

Key: Each = 2 animals

How many duck and chickens are there?

•Let’s skip count the ducks by 2’s. Ducks =•Now let’s do the same thing for chickens. Chickens=•Now let’s add them together.

•So 8+6=14 or 6+8=14

Animals on Brittany’s farm

Chickens

Cows

Ducks

Sheep

Key: Each = 2 animals

The numbers 6,8 and 14 can be used to make a fact family.

• What is a fact family?• A fact family is a set of related addition and

subtraction number sentences that use the same numbers.

• What are the number sentences in the 6,8,and 14 fact family?

Write another fact family that uses the number 8.

What is the fact family for 6, 6, and 12?

• Why does this fact family only have two facts?

• Fact families are examples of inverse operations.

• What are inverse operations?• Inverse operations are opposites. So addition

and subtraction are inverse operations.• What is another example of inverse

operations?

Let’s practice

• Get out your math book and turn to p. 3• Let’s do 2-7 together.

Math task

1. MB p. 3 numbers 8-26 even. When you finish stack them neatly in one stack on my desk.

2. Write the facts for these fact families in your math journal: 4,2 and 6; 6, 2, and 8; 1, 14, and 15; 8, 2, and 10; and 6, 13; and 19.

3. Math game from the black box.

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