How do you add -3 + (-6)

and how does that relate to 3 + 6 ?

In this lesson you will learn to add two positive or two

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 two negative integers and getting a positive sum.

-5 + (-7) = 12--5 + (-7) = -12

Let’s ReviewCore Lesson

Positive NumbersNegative Numbers

Positive Direction

Negative Direction

Let’s ReviewCore Lesson3 + 6

Positive Numbers

Positive Direction

3 6

9

=9

Let’s ReviewCore Lesson

Negative Numbers

Negative Direction-3 + (-6)

-3-6

-9

=-9

Let’s ReviewCore Lesson

-3 + (-6) =-9

3 + 6 = 9

In this lesson you have learned add two positive or two

negative integers by using a number line.

Let’s ReviewGuided Practice

Simplify (-4) + (-7).

Let’s ReviewGuided Practice

What is the sum of 6 and 9?

Let’s ReviewExtension Activities

Try graphing two addition problems with opposite numbers on the same graph.

For example, use 12 + 8 and -12 + (-8).

Write about what you notice.

Let’s ReviewExtension Activities

Draw two number lines. On the first, graph -9 + (-13). On the second, graph -13 + (-9).

Compare and contrast the graphs.

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?