Transcript Adding and Subtracting Positive and Negative Numbers

Donna Reynolds
Impact of Technology Assignment 1.17
My Powerpoint will be used to teach fifth grade math-specifically
adding and subtracting positive and negative numbers.
This is connected with the Massachusetts Curriculum Frameworks
learning standard for grades 5 and 6. as follows:
•6 N 6 Find and position integers, fractions, mixed numbers
and decimals both positive and negative on the number line.
•6 N 7 Compare and order integers (including negative integers) and
positive fractions, mixed numbers, decimals, and percents.
Subtracting negative numbers is included in the Everyday Math Program.
The concept of adding and subtracting positive and negative numbers
Can be challenging for students. The Powerpoint will introduce the
concept and provide visuals of the rules to follow. There are also links to
Websites to provide further reinforcement with tutorials, games, and
practice problems.
Adding and Subtracting
Positive and Negative Numbers
-7 + 5 = -2
First, let’s look
at the
number line.
Sure!
Right!
THE NUMBER LINE
Negative numbers are to the Positive numbers are to the
right of zero.
left of zero.
Adding:
RULE 1:
When adding numbers
with
like signs, add
using the same sign.
Forward to
Slide 22
+
+
+
=
+
+
3
=
5
-
+
-
-2
+
-3
2
=
=
-5
Add
using the
same sign.
Makes
sense!
Adding:
RULE 2:
When adding
numbers with
unlike signs,
use the sign of the
larger number and
subtract.
Sounds
tricky!
Forward to
slide 22
+
+
-
=
Use the sign of the larger
number and subtract.
For Example:
+5
+
Oh,,,
I see.
-3
=
+2
The number 5 is larger than 3 so use a positive sign in the sum.
-- 5
+
3
= -2
The number 5 is larger than 3 so use a negative sign in the sum.
+5
+
-
+
-3
+
-
+
-
=
+2
+
+
Do you see
there is
a balance of
+2 ?
+3
-
-
+
-
+
+
-5
=
-2
-
Do you see
there is
a balance of
-2 ?
+
Try this…..
9 + -3 = ?
????
+9 + -3 = +6
Exactly!
9 is larger, so
subtract and use
a positive sign
Try this…..
-7
+ +2 = ?
????
-7 + +2 = 5
Exactly!
7 is larger, so subtract
the two numbers and
use a negative sign.
Subtracting
Rule 3:
To subtract a
positive or negative
number, add the
opposite number.
Yikes
!
Forward to Slide 22
The opposite
of positive 7 is
negative 7
I see!
The opposite
of negative 7
is positive 7
I get it!
To subtract a positive or negative
number, add the opposite number.
For Example…….
+7
-
+5
is
+7 + -5 = +2
And…
-7
-
-5
is
-7
+ +5 = -2
And…..
7
- -5
is
+7 + +5 = +12
And look….
-7 - +5
is
-7
+ -5 = -12
So….subtracting a
negative number
is like
adding a positive.
And… subtracting
a positive is like
adding a negative.
Precisely!!!
If you need to
review the
rules click
the buttons
below.
Adding with like signs
Adding with unlike signs
Subtracting
Online Practice
Adding and Subtracting
Positive and Negative Numbers
Adding with
Color Chips
Subtracting with
Color Chips
Online Games
Adding and Subtracting
Positive and Negative Numbers
“Eat the Fish”
*(must use Internet Explorer)
Fun Brain
“Line Jumper”
That’s how to add and subtract
Positive and negative numbers.
If you would like to review, you may
Start over by clicking the arrow.
-7 + 5 = -2