Subtraction from
Addition
Objectives To review the – 0 and – 1 shortcuts; and to guide
children
to identify the subtraction facts related to given
c
addition facts.
www.everydaymathonline.com
ePresentations
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Practice
EM Facts
Workshop
Game™
Teaching the Lesson
Key Concepts and Skills
• Practice subtraction facts.
[Operations and Computation Goal 1]
• Use dominoes to model related addition
and subtraction facts.
[Operations and Computation Goal 1]
• Identify and use patterns to solve
subtraction facts.
[Patterns, Functions, and Algebra Goal 1]
• Use symbols to write number sentences
for fact families.
[Patterns, Functions, and Algebra Goal 2]
Key Activities
Children make up and share number stories
that are solved by subtraction, discover and
practice the –0 and –1 shortcuts, and use
dominoes to generate related addition and
subtraction facts.
Family
Letters
Assessment
Management
Common
Core State
Standards
Ongoing Learning & Practice
1 2
4 3
Practicing Addition and
Subtraction Facts
My Reference Book, pp. 122, 123,
148 and 149
per partnership: 4 each of number
cards 0–10 (from the Everyday Math
Deck, if available)
Children review addition and
subtraction facts by playing Addition
Top-It and Subtraction Top-It.
Math Boxes 2 6
Math Journal 1, p. 36
Children practice and maintain skills
through Math Box problems.
Home Link 2 6
Curriculum
Focal Points
Interactive
Teacher’s
Lesson Guide
Differentiation Options
READINESS
Exploring Domino Facts
Math Masters, p. 32
dominoes
Children explore the relationship between
addition and subtraction facts using a
concrete model.
ENRICHMENT
Exploring Dice Subtraction
with Negative Differences
Math Masters, p. 33
dice number line
Children use dice combinations to explore
differences and patterns in single-digit
subtraction.
Math Masters, p. 31
Children practice and maintain skills
through Home Link activities.
Ongoing Assessment:
Recognizing Student Achievement
Use an Exit Slip (Math Masters,
page 415).
[Patterns, Functions, and Algebra Goal 3]
Key Vocabulary
subtraction number story –0 facts –1 facts –0 shortcut –1 shortcut
Materials
Math Journal 1, p. 35
Home Link 25
Math Masters, p. 415
1 domino per child slate 10 counters and
10 cubes (optional)
Advance Preparation
Teacher’s Reference Manual, Grades 1–3 pp. 197, 198
Lesson 2 6
121
Mathematical Practices
SMP2, SMP4, SMP5, SMP6, SMP8
Getting Started
Content Standards
2.OA.1, 2.OA.2, 2.NBT.9, 2.MD.6
Mental Math and Reflexes
Math Message
Pose doubles-plus-1 and doubles-plus-2 facts.
Suggestions:
Make up a story for the number model 10 - 3 = 7.
6 + 6 = ? 12
8 + 8 = ? 16
7 + 7 = ? 14
6 + 7 = ? 13
8 + 9 = ? 17
7 + 8 = ? 15
NOTE Change-to-less (also called take-away
or taking-from) is the meaning of subtraction
most often encountered in schoolwork. The
comparison meaning of subtraction does not
involve take-away, because nothing is actually
taken away; the two sets of quantities are
just being compared. Children are not
expected to categorize subtraction stories as
“change-to-less” or “comparison” at this time.
6 + 8 = ? 14
8 + 10 = ? 18
7 + 9 = ? 16
Home Link 2 5
Follow-Up
Check that children were able to find the correct
path from the child to the ice-cream cone.
1 Teaching the Lesson
Math Message Follow-Up
WHOLE-CLASS
ACTIVITY
Write 10 - 3 = 7 on the board. Ask children to share their
subtraction number stories. Draw an empty unit box. Have
children suggest a label for each number story and write it in the
unit box. Expect most of the children’s number stories to be one of
two types:
Change-to-Less
Start with a number of items. Decrease the number of items.
Find out the number of items after the number is decreased.
For example: Tavon had 10 model cars. He lost 3 model cars.
How many model cars does Tavon have now? 7 model cars
0
1
2
3
4
5
6
7
8
9 10
Change-to-Less
Children can model change-to-less number stories by
representing the number in the story with counters. They
remove the appropriate number of counters as described in
the story. The number of counters remaining is the difference.
They can also model the story on a number line by starting at
the number showing the number of items and counting back
the appropriate number of spaces as described in the story. The
number they land on is the difference. (See margin.)
Comparison
Two separate quantities are known. Compare them by finding
the difference between them. Tell how many more or less.
For example: Supat has 10 model cars. Neal has 3 model cars.
How many more model cars does Supat have? 7 more model cars
difference
0
1
2
3
4
5
6
7
8
9 10
difference
Comparison
122
Unit 2 Addition and Subtraction Facts
Children can model comparison number stories with sets of
cubes, each representing the numbers being compared. They
determine the answer by visually comparing the two sets of
cubes. They can also model the story on a number line. (See
margin.)
Discussing the -0 and
the -1 Shortcuts
WHOLE-CLASS
ACTIVITY
Write some -0 facts and -1 facts on the board; do not include
the differences. Use both horizontal and vertical forms.
Examples:
5-0=
=9-1
=8-0
3
-1
9
-0
Ask children to copy and complete the facts on their slates. See
whether they can describe the -0 shortcut and the -1 shortcut.
If 0 is subtracted from any number, that number does not change.
If 1 is subtracted from any number, the result is the next
smaller number.
5
4
9
9
+ 4 + 5 - 5 - 4
9
9
4
5
Write this problem on the board: 87 - 0 =
. After a volunteer
has given the answer, ask someone else to check the answer on a
calculator. Try several other examples with 2- and 3-digit
numbers, and with some large numbers, just for fun!
Follow the same procedure with several -1 examples. Use 2- and
3-digit numbers and a few large numbers.
Using Dominoes to Generate
Related Addition and
Subtraction Facts
WHOLE-CLASS
ACTIVITY
PROBLEM
PRO
PR
P
RO
R
OB
BLE
BL
LE
L
LEM
EM
SO
S
SOLVING
OL
O
LV
LV
VIN
IN
ING
Adjusting the Activity
So children can recognize the
subtraction facts using dominoes, have them
erase or cover up one side of the domino.
For example: Nine dots in all. Take away the
5 dots on one side by erasing them. Four
dots remain. So, 9 - 5 = 4.
AUDITORY
KINESTHETIC
TACTILE
VISUAL
Draw a domino on the board. Help children discover a set of
related facts shown by the domino. For example, for a domino with
5 dots on one half and 4 dots on the other, ask:
Date
●
What is the total number of dots shown? 9
For Problems 1 through 7, write 2 addition facts and 2 subtraction facts
for each domino.
●
Which addition facts describe this domino? 5 + 4 = 9 and
4+5=9
1.
Student Page
Time
LESSON
26
2.
+
Remind children about turn-around facts.
Write the numbers 5, 4, and 9 on the board. Then write the two
addition facts just named: 5 + 4 = 9 and 4 + 5 = 9.
●
Which subtraction facts can you write using the three numbers
5, 4, and 9? 9 - 5 = 4 and 9 - 4 = 5 Write these two
subtraction facts on the board.
Domino Facts
2
4
2 + 4
6
6
-
6
2
4
-
6
4
2
3.
6
4
10
+
4
6
10
-
10
4
6
-
10
6
4
+
8
6
14
+
6
8
14
-
14
6
8
-
14
8
6
+
9
5
14
+
5
9
14
-
14
5
9
-
14
9
5
4.
5
+ 7
12
7
+ 5
12
12
- 7
5
12
- 5
7
3
+ 8
11
8
+ 3
11
11
- 8
3
11
- 3
8
5.
Continue with other domino examples in the same way.
+
6.
Try This
8. Write one addition fact and
one subtraction fact.
7.
+
9
0
9
+
0
9
9
-
9
0
9
-
9
9
0
+
9
9
18
-
18
9
9
Math Journal 1, p. 35
EM3cuG2MJ1_U02_21_52.indd 35
1/7/11 12:31 PM
Lesson 2 6
123
Student Page
Date
Practicing Domino Facts
Time
LESSON
Math Boxes
26
(Math Journal 1, p. 35)
2. What is the temperature? Fill
1. Fill in the missing numbers.
in the circle next to the best
answer.
144
154
164 165
C 52 degrees
3. Write the sums.
4. Write these numbers in order
15
16
17
18
10 + 6 =
10 + 7 =
10 + 8 =
50
D 56 degrees
96
10 + 5 =
60
62 degrees
B
166
Children write the addition and subtraction facts generated by
each domino pattern on the journal page. The final problems
include special features that may cause some children difficulty.
The double-9 domino has only two related facts, not four:
9 + 9 = 18 and 18 - 9 = 9. The domino with 9 dots on the top
and zero dots on the bottom may confuse children. Make sure
children realize that the blank half of the domino stands for zero.
The four related facts for this domino are 9 + 0 = 9, 0 + 9 = 9,
9 - 0 = 9, and 9 - 9 = 0.
°F
55 degrees
A
156
155
from smallest to largest. Begin
with the smallest number.
Unit
INDEPENDENT
ACTIVITY
133, 146, 129, 151
129 , 133 , 146 , 151
6. What time is it?
5. Put an X on the digit in the
7
tens place.
456
:
15
11
10
What time
will it be in
15 minutes?
309
7
:
12
2
3
8
4
7
30
Ongoing Assessment:
Recognizing Student Achievement
1
9
5
6
80 81
10
Math Journal 1, p. 36
EM3cuG2MJ1_U02_21_52.indd 36
1/10/11 10:14 AM
Exit Slip
Use an Exit Slip (Math Masters, page 415) to assess children’s understanding of
the turn-around facts. Give each child a domino. Have them write two addition
and two subtraction facts for that domino. Children are making adequate
progress if they can write the corresponding addition problem and the
turn-around fact. Some children may be able to successfully write two
corresponding subtraction problems.
[Patterns, Functions, and Algebra Goal 3]
2 Ongoing Learning & Practice
Practicing Addition and
PARTNER
ACTIVITY
Subtraction Facts
(My Reference Book, pp. 122, 123, 148, and 149)
Home Link Master
Name
Date
HOME LINK
Time
26
Domino Facts
Family
Note
Today we learned that addition problems and subtraction problems are related. For example,
5 + 3 = 8 can be rewritten to show two related subtraction facts: 8 - 5 = 3 and 8 - 3 = 5.
Each domino shown below can be used to write 2 addition facts and 2 related
subtraction facts.
25
Please return this Home Link to school tomorrow.
Write 2 addition facts and 2 subtraction facts for each domino.
1.
2.
7
+3
3
+7
10
10
-3
7
10
10
-7
+
3
3.
9
6
15
+
6
9
15
-
15
6
9
-
15
9
6
4.
+
8
7
15
+
7
8
15
-
15
7
8
-
15
8
7
7. 5 + 7 =
13
12
+
6.
5
9
14
+
9
5
14
14
-
14
9
5
-
14
5
9
Unit
=8+6
8. 7 + 9 =
16
Math Masters, p. 31
EM3MM_G2_U02_025-055.indd 31
124
Math Boxes 2 6
INDEPENDENT
ACTIVITY
(Math Journal 1, p. 36)
Write the sums. Tell someone at home what you know
about doubles-plus-1 and doubles-plus-2 facts.
5. 6 + 7 =
Children practice addition and subtraction facts by playing Addition
Top-It and Subtraction Top-It. Provide time for children to play
both games. Children were introduced to Addition Top-It in Lesson
1-4. For instructions, see My Reference Book, pages 122 and 123.
Subtraction Top-It is played similarly. See My Reference Book, pages
148 and 149. Read the rules with the class and model a round or two
prior to having children play in partnerships or small groups.
1/5/11 2:33 PM
Unit 2 Addition and Subtraction Facts
Mixed Practice Math Boxes in this lesson are paired with
Math Boxes in Lesson 2-8. The skills in Problems 5 and 6
preview Unit 3 content.
Teaching
g Master
Home Link 2 6
Name
INDEPENDENT
ACTIVITY
Date
LESSON
Domino Facts
26
Fill in the missing dots and missing numbers for each problem
below. Hint: You can look at dominoes to help you figure out
what the dots look like.
(Math Masters, p. 31)
Home Connection Children use dominoes to generate
and solve related addition and subtraction facts. Children
also practice doubles-plus-1 and doubles-plus-2 facts.
7
1.
4
3 Differentiation Options
Exploring Domino Facts
5
6
7
12
5.
6
4
15
6.
6
6
5
6
9
Answers vary.
7.
INDEPENDENT
ACTIVITY
5–15 Min
Try This
Explain when you think subtraction facts might help you solve
the problems above. Sample answer: When I know the total
To explore the relationship between addition and subtraction facts
using a concrete model, have children use dominoes to model facts.
Children complete Math Masters, page 32. When they have finished
the page, discuss when they added and when they subtracted to find
the missing numbers. (Note that some children may add up instead
of subtracting when solving the domino problems.)
Exploring Dice Subtraction
3
12
3.
Make up one of your own.
(Math Masters, p. 32)
ENRICHMENT
11
2.
10
4.
READINESS
Time
number of dots and the number of dots on half of the domino,
I can subtract to find the other number of dots.
Math Masters, p. 32
EM3MM_G2_U02_025-055.indd 32
1/5/11 2:33 PM
INDEPENDENT
ACTIVITY
5–15 Min
with Negative Differences
(Math Masters, p. 33)
To apply children’s understanding of subtraction, have them solve
randomly generated single-digit subtraction problems. They record
their work on Math Masters, page 33. Discuss the patterns they
see on the page. When the two numbers are switched in the
problem, the differences are the same distance from zero on the
number line. When you subtract the larger number from the
smaller number, the difference is a negative number.
Teaching Master
Name
LESSON
26
Date
Time
Dice Subtraction
For each problem below:
1. Roll two dice.
2. Record the numbers you rolled.
3. Write two subtraction number models for the numbers
you rolled.
Planning Ahead
If children have not cut out the Fact Triangles from Activity
Sheets 1 and 2, have them do that soon. They will be used in
Lesson 2-7.
4. Use a number line to solve your problems. (Hint:
Sometimes your answers will be negative numbers.)
Example:
I rolled 4 and 5.
5 – 4 = 1 and 4 – 5 = -1.
1. I rolled
2. I rolled
3. I rolled
-
and
.
=
and
=
and
-
=
-
=
-
=
.
.
=
Try This
Each time you roll the dice, how could you use one of your
subtraction problems to help you solve the other?
Sample answer: Each answer will be the same
distance from 0 on the number line.
Math Masters, p. 33
EM3MM_G2_U02_025-055.indd 33
1/5/11 2:33 PM
Lesson 2 6
125