&&66
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NS 2.2*2$
Use the inverse
relationship between addition and subtraction to
H[DPSOHVXEWUDFW±E\ILQGLQJWKHQXPEHUWKDWPDNHVZKHQDGGHGWR
UNDERLYING SKILLS AND CONCEPTS:
solve problems.
inverse operations
Understand Fact Families
a
K
ey Ide
Addition and subtraction facts that have the same
numbers are called a fact family.
3, 4, and 7 are in the same fact family.
3!4"7
4!3"7
7#3"4
E x am p l E
7#4"3
3
7
!"#
4
1
What addition story does the picture tell?
There are 5 kites and
3 more kites.
How many kites in all?
A – © CSL Associates, Inc. All rights reserved.
5!3"8
3!5"8
E x am p l E
2
What subtraction story does the picture tell?
There were 8 kites.
3 flew away.
How many are left?
8#3"5
There were 8 kites. Now there
are 5. How many flew away?
8#5"3
Chapter 9 – Lesson 2
page 101
Name
P RAC T I C E
Use the picture.
Write the addition and subtraction sentences.
1
2
10
4
6
2
6
4 6 10
6 4 10
10 4 6
10 6 4
4
2
6
6
2
4
4
2
4
6
6
2
4
Complete each fact family.
9 6 15
718
6 9 15
178
15 6 9
871
15 9 6
817
Math
Reasoning
5
4
Number Sense
MR 1.1
Which does not belong in the fact family?
Explain.
7 5 12
752
12 5 7
5 7 12
7 5 2. Possible explanation: A fact family
has 3 numbers that are the same. 5, 7, and 2 are
in a different family from 5, 7, and 12.
page 102
Chapter 9 – Lesson 2
A – © CSL Associates, Inc. All rights reserved.
3
Name
…at home!
P RAC T I C E
Use the picture.
Write the addition and subtraction sentences.
1
2
9
4
4
5
9
9
5
4
4
5
5
5
2
9
9
5
4
3
2
5
5
2
3
3
2
3
5
5
2
3
Complete each fact family.
9 8 17
516
8 9 17
156
17 8 9
651
17 9 8
615
Math
Reasoning
5
4
Number Sense
MR 1.1
Which does not belong in the fact family?
Explain.
6 8 14
862
14 8 6
8 6 14
8 6 2. Possible explanation: A fact family
has 3 numbers that are the same. 6, 8, and 2 are
in a different family from 6, 8, and 14.
page 68
Home Resource and Homework
Chapter 9 Lesson 2
A – © CSL Associates, Inc. All rights reserved.
3
MCX94TEG1Ch01_30.v8.4.1 2/19/01 19:20 Page 187
Name
P RAC T I C E
Use the picture.
Write the addition and subtraction sentences.
1
2
10
4
6
2
6
4 6 10
6 4 10
10 4 6
10 6 4
4
2
6
6
2
4
4
2
4
6
6
2
4
Complete each fact family.
A – © CSL Associates, Inc. All rights reserved.
3
9 6 15
718
6 9 15
178
15 6 9
871
15 9 6
817
Math
Reasoning
5
4
Number Sense
MR 1.1
Which does not belong in the fact family?
Explain.
7 5 12
752
12 5 7
5 7 12
7 5 2. Possible explanation: A fact family
has 3 numbers that are the same. 5, 7, and 2 are
in a different family from 5, 7, and 12.
Chapter 9 – Lesson 2
Student Book Page
page 102
Name
…at home!
P RAC T I C E
Use the picture.
Write the addition and subtraction sentences.
1
2
9
4
4
5
9
9
5
4
4
5
5
5
2
9
9
5
4
3
2
5
5
2
3
3
2
3
5
5
2
3
Complete each fact family.
9 8 17
516
8 9 17
156
17 8 9
651
17 9 8
615
Math
Reasoning
5
4
Number Sense
MR 1.1
Which does not belong in the fact family?
Explain.
6 8 14
862
14 8 6
8 6 14
8 6 2. Possible explanation: A fact family
has 3 numbers that are the same. 6, 8, and 2 are
in a different family from 6, 8, and 14.
page 68
Home Resource and Homework
Chapter 9 Lesson 2
A – © CSL Associates, Inc. All rights reserved.
3