SCUSD Common Core Mathematics Lesson Planning Guide
Unit Title: Place Value and Multi-Digit
Arithmetic
Lesson: 5A - Addition and Subtraction are
Inverse Operations.
Approx. time:
45 minutes
A. Focus and Coherence
Students will know…
 Addition and subtraction are inverse operations
Students will be able to…
 Plot inverse operations on a number line
Student prior knowledge:
 Addition facts
 Subtraction facts
CCSS-M Standards:
3.NBT.2 Fluently add and subtract within 1000 using
strategies and algorithms based on place value, properties
of operations, and/or the relationship between addition
and subtraction.
B. Evidence of Math Practices
What will students produce when they are making sense,
persevering, attending to precision and/or modeling, in
relation to the focus of the lesson?


When I subtract and add the same numbers they are
called inverse operations.
I can use a number line to plot inverse operations
Which math concepts will this lesson lead to?
 Properties of addition and subtraction
 Multiplication
Guiding Question(s)
 How is subtraction related to addition?
Formative Assessments
 Check for Understanding with students plotting and labeling inverse operations on a number line.
Anticipated Student Preconceptions/Misconceptions
o Inverse operations have different digits
o Subtracting Math Facts and adding math facts from the same family have different answers.
Materials/Resources
Class set of black and red pens
Class set of the Inverse Operations Number Line
C. Rigor: fluency, deep understanding, application and dual intensity
What are the learning experiences that provide for rigor? What are the learning experiences that provide for evidence of
the Math Practices? (Detailed Lesson Plan)
Warm Up

Using your fingers, display the answers to these number sentences….What is the sum of 2 + 3 =? What is the sum of
3 + 2 =? What is the difference of 5 – 2 =? What is the difference of 5 – 3 =? Great! I will give you 5 seconds to think
about what do these numbers have in common? Let’s do a whip-around and quickly give me your answer.
Grade: 3
Unit: Place Value and Multi-Digit Arithmetic
Lesson 5A, Pg. 1
Lesson
T- “These number sentences are known as fact families. Turn to your elbow partner neighbor and explain the properties
of fact families”
o Give the students 1 minute of independent think-time and 1 minute of pair-share, prior to asking for 1-3
students to share out.
T - “What is a number line?” Turn to your face partner and give them a quick definition of a number line. 5 seconds to
think…now tell.
T- As your math learning matures, so does the language and skills of math problems. So these fact families are also
known as inverse operations. We will learn how to represent inverse operations using a number line. Repeat after me,
“Inverse Operations”, now say those words to your elbow partner; now say those words to your face partner.
T- One more time…”What are we learning today?
S- “INVERSE OPERATIONS”
T- It is so important to learn and become an expert with inverse operations, so that you will be able to extend your
mathematical skills with Properties of operations, multiplication, and division.
T – Using a number line, ask students to plot inverse operations with their sums and differences on the number line.
Using the ELMO (document reader), display the number sentences 2 + 3 = 5 and 5 – 2 = 3.
o Ask the students who would like to demonstrate how to plot inverse operations on a number line.
o *If a student volunteers, have that student demonstrate using plotting on the number line,
o If the student is correct with their demonstration, then continue with the lesson.
[If no one volunteers or the student does not do the correct demonstrate, then do the following]
[Direct Teaching, if necessary….(see example), model how to plot and label the inverse operations on the number line.]
2+3=5
Inverse Operations Number Sentences.
5-2=3
1
2
3
4
5
6
7
2 + 3 = 5 and 5 – 2 = 3
[If there is a volunteer and the modeling is correct, then continue lesson from this point]
T- Give students the attached sheet and allow 15 minutes to complete the worksheet.
Students should use a black pen for addition number sentences and red pen for subtraction sentences.
Closure
You will now create your own inverse operations and plot them on the number line.
Suggested Homework/Independent Practice
Give students three blank number lines and have them create their own inverse operations and plot them on then
number line. See Homework sheet below.
Grade: 3
Unit: Place Value and Multi-Digit Arithmetic
Lesson 5A, Pg. 2
Inverse Operations Using the Number Line
o Use black pen for addition problems
o Use red pen for subtraction problems
10 + 10 = 20
20 – 10 = 10
11 + 7 = 18
18 – 7 = 11
20
21
22
21 + 15 = 36
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38 39 40
36 – 15 = 21
How do you know that subtraction is related to addition?
Grade: 3
Unit: Place Value and Multi-Digit Arithmetic
Lesson 5A, Pg. 3
HOMEWORK
Name_____________________________________ Date___________________________________
___ + ____ = _____
20
21
22
23
____ + ____ = _____
24
25
26
27
___ + ____ = _____
20
21
22
___ + ____ = _____
Grade: 3
23
28
29
30
31
32
33
34
35
36
37
38 39 40
____ + ____ = _____
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38 39 40
_____ + ____ = _____
Unit: Place Value and Multi-Digit Arithmetic
Lesson 5A, Pg. 4