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?