When you add a positive number and negative number, is the answer positive
or negative?
In this lesson you will learn to add positive and negative
integers by using a number line.
Let’s ReviewLet’s Review
What’s an integer?
Integers include positive and negative whole numbers as well as 0.
...-3, -2, -1, 0, 1, 2, 3 ...
More Examples:
-5 3 28 -9 1 0
Let’s ReviewLet’s Review
What’s addition?
Addition is the process of joining two groups.
7 + 11 = 18
addend addend sum
Let’s ReviewA Common Mistake
Adding a positive and negative integer like two positives and applying the sign of the number with the larger absolute
value.
-4 + 6 = 10-4 + (-6) = -10-
Let’s ReviewCore Lesson
Positive NumbersNegative Numbers
Positive Direction
Negative Direction
Let’s ReviewCore Lesson
8 + (-2)
Positive Numbers
8-2
6
=6Negative Direction
Let’s ReviewCore Lesson
8 + (-13)
Positive Numbers
8-13
-5
=-5Negative Direction
Let’s ReviewCore Lesson
8
-13
-5
8-2
6
8 + (-13)=-5
8 + (-2) =6
In this lesson you learned to add positive and negative
integers by using a number line.
Let’s ReviewGuided Practice
-12 + 8
-12 + 15
Let’s ReviewGuided Practice
What is the sum of 14 and -5?
Let’s ReviewExtension Activities
Try graphing two addition problems with opposite numbers on the same graph.
For example, use -15 + 3 and 15 + (-3).
Write about what you notice.
Let’s ReviewExtension Activities
Use what you know about adding positive and negative numbers to fill out the table using mental math.
Problem Cross 0 on number line?
Positive or negative sum?
Ex: 5 + (-3) No Positive
-15 + 10
9 + (-23)
-17 + 30
20 + (-8)
2 + (-14)
Let’s ReviewExtension Activities
Partner Game:Write the integers -20 through +20 on small pieces of paper and turn them face down.
You and your partner pull 2 numbers. Sum the integers by graphing the process on a number line. The person with the greater sum gets a point. Repeat.
Let’s ReviewQuick Quiz
Simplify 9 + (-7).
What is the sum of -6 and -13?