&&66
$SSO\SURSHUWLHVRIRSHUDWLRQVDVVWUDWHJLHVWRDGGDQGVXEWUDFW
NS 2.1*2$
Understand
and use the inverse relationship between addition
([DPSOHV
and subtraction (e.g.,LVDOVRNQRZQ&RPPXWDWLYHSURSHUW\RIDGGLWLRQ
an opposite number sentence for 8 ! 6 "
,I LVNQRZQWKHQ
14 is 14 – 6 " 8) to solve problems and check solutions.
7RDGGWKHVHFRQGWZRQXPEHUVFDQEHDGGHGWRPDNHDWHQVR
$VVRFLDWLYHSURSHUW\RIDGGLWLRQ6WXGHQWVQHHGQRWNQRZWKHIRUPDOWHUPV
IRUWKHVHSURSHUWLHV
&&66 *2$
UNDERLYING SKILLS AND CONCEPTS:
addition basic facts;
subtraction basic facts
)OXHQWO\DGGDQGVXEWUDFWZLWKLQXVLQJPHQWDOVWUDWHJLHV%\HQG
Use Fact Families and Inverse Operations
a
K
ey Ide
9
A fact family
shows how three
numbers are related.
You can write addition
and subtraction
sentences using the
same 3 numbers in
a family.
7!2$9
2!7$9
9#2$7
9#7$2
7
2
The 9 • 7 • 2 Fact Family
E x am p l E
1
B – © CSL Associates, Inc. All rights reserved.
4, 3, and 7 make a fact family.
7
There are two addition facts
and two subtraction facts
in this fact family.
E x am p l E
3
4
2
5, 5, and 10 make a doubles
fact family.
There is one addition fact
and one subtraction fact
in this family.
Chapter 9 – Lesson 3
7#3$4
7#4$3
4!3$7
3!4$7
10
10 # 5 $ 5
5 ! 5 $ 10
!"#
5
5
page 103
Name
P RAC T I C E
Write the facts in each family.
1
4, 4, 8
448
2
8, 9, 17
844
8 9 17
9 8 17
17 8 9
17 9 8
6, 7, 13
6 7 13
4
4, 5, 9
459
7 6 13
549
13 6 7
945
13 7 6
954
Do the following numbers form a fact family? Write YES or NO. Explain.
5
6, 6, 12
YES
6
5, 1, 6
YES
7
7, 3, 10
YES
8
9, 6, 3
YES
9
1, 2, 4
NO
10
1, 1, 1
NO
Math
Reasoning
11
Number Sense
MR 2.3
How many fact families can you find that have 12 as the
greatest number? Make a list. There are 7 possibilities.
12, 0,12; 11, 1, 12; 10, 2, 12; 9, 3, 12; 8, 4, 12; 7,
5, 12; 6, 6, 12
page 104
Chapter 9 – Lesson 3
B – © CSL Associates, Inc. All rights reserved.
3
Name
P RAC T I C E
Write the facts in each family.
1
3, 3, 6
336
2
5, 6, 11
633
5 6 11
6 5 11
11 6 5
11 5 6
7, 8, 15
8 7 15
4
3, 4, 7
437
7 8 15
347
15 8 7
743
15 7 8
734
Do the following numbers form a fact family? Write YES or NO. Explain.
5
7, 7, 14
YES
6
2, 2, 5
NO
7
2, 3, 6
NO
8
8, 5, 3
YES
9
6, 4, 10
YES
10
6, 1, 7
YES
Math
Reasoning
11
Number Sense
MR 2.3
How many fact families can you find that have 16 as the
greatest number? Make a list. There are 9 possibilities.
16, 0,16; 15, 1, 16; 14, 2, 16; 13, 3, 16; 12, 4, 16;
11, 5, 16; 10, 6, 16; 9, 7, 16; 8, 8, 16.
page 70
Home Resource and Homework
Chapter 9 Lesson 3
B – © CSL Associates, Inc. All rights reserved.
3
MCX94TEG2Ch01_30.v9.4.1 2/19/01 19:47 Page 191
Name
P RAC T I C E
Write the facts in each family.
1
448
4, 4, 8
2
8, 9, 17
844
8 9 17
9 8 17
17 8 9
17 9 8
B – © CSL Associates, Inc. All rights reserved.
3
6, 7, 13
6 7 13
4
4, 5, 9
459
7 6 13
549
13 6 7
945
13 7 6
954
Do the following numbers form a fact family? Write YES or NO. Explain.
5
6, 6, 12
YES
6
5, 1, 6
YES
7
7, 3, 10
YES
8
9, 6, 3
YES
9
1, 2, 4
NO
10
1, 1, 1
NO
Math
Reasoning
11
Number Sense
MR 2.3
How many fact families can you find that have 12 as the
greatest number? Make a list. There are 7 possibilities.
12, 0,12; 11, 1, 12; 10, 2, 12; 9, 3, 12; 8, 4, 12; 7,
5, 12; 6, 6, 12
Chapter 9 – Lesson 3
Student Book Page
page 104
Name
P RAC T I C E
Write the facts in each family.
1
3, 3, 6
336
2
5, 6, 11
633
5 6 11
6 5 11
11 6 5
11 5 6
7, 8, 15
8 7 15
4
3, 4, 7
437
7 8 15
347
15 8 7
743
15 7 8
734
Do the following numbers form a fact family? Write YES or NO. Explain.
5
7, 7, 14
YES
6
2, 2, 5
NO
7
2, 3, 6
NO
8
8, 5, 3
YES
9
6, 4, 10
YES
10
6, 1, 7
YES
Math
Reasoning
11
Number Sense
MR 2.3
How many fact families can you find that have 16 as the
greatest number? Make a list. There are 9 possibilities.
16, 0,16; 15, 1, 16; 14, 2, 16; 13, 3, 16; 12, 4, 16;
11, 5, 16; 10, 6, 16; 9, 7, 16; 8, 8, 16.
page 70
Home Resource and Homework
Chapter 9 Lesson 3
B – © CSL Associates, Inc. All rights reserved.
3