Download Adding and Subtracting Integers Methods

A.09
Do Now
Write an expression and find the answer to this problem:
Franklin the frog started at 6 on a number line. He then
jumped back 8, forward 3, back 5, forward 11, and
finally, back 1. Where did he end up?
Show your work!
Do Now - Answer
Franklin the frog started at 6 on a number line. He then
jumped back 8, forward 3, back 5, forward 11, and
finally back 1. Where did he end up?
Objective
 Today, I will add and subtract integers using three
different methods.
Sign on a number
 Tells us the direction the number is moving
 Positive (+) moves Right
 Negative (-) moves Left
Sometimes it can be tricky!
What is the sign on the “8”
in every problem below?



Vote only using your arms/
hands!
10 + 8

10 - 8

-8 + 10

8 + (-10)
10 + (-8)
8 - 10
Now that we know the signs, time to check out 3
methods for adding and subtracting integers
 3 methods!!
1) Tile method
2) Forces method
3) Money Method
Tile Method
 This method relies on the use of zero pairs.
 One positive and one negative make a zero pair because
 Draw a + sign for positive
 Draw a – sign for negative.
Tile Method – Example
-8+5
positive
negative
What’s left over?
-3
What’s left over?
2
(-3) + 6 – 1
positive
negative
Forces Method
 Imagine the numbers are trying to push an object in a
certain direction
 Positive forces go to the right.
 Negative forces go to the left.
 The number tells us how strong they are.
Forces Method - Example
 Are they working together or against each other?
 If they are working together, add up their strengths
5 + 8 = 13
Negative direction
Answer: - 13
 If they are working against each other, who wins and by
how much?
Opposite!
Positive sign wins by 2!
Answer: +2
Money Method
 Imagine that the numbers are amounts of
money in a bank account.
means to spend, take out, or owe money.
means to deposit, put in, or earn money.
Example
 The first number tells how much you start with.
 The sign and the next number tell what you do to that amount.
350 – 425
(bank account)
start with $350 in bank
friend buys you a ticket to the Warriors play-off game: owe $425
Answer: -$75
-130 – 14
(credit card bill)
owe $130 on credit card bill
buy a burger and garlic fries at game - owe $14 more
Answer: - $144
Practice Time!
 Time to figure out which method works best for YOU!
 With your partner complete parts 1, 2, 3, and 4.
 You must get a star on each section to move on.
 Once you have been starred, do number 5 (parts A
through J – yes, that’s everything!)
Number 5 Answers:
A)
4
B)
-14
C)
-24
D)
-61
E)
-18
F)
-185
G)
-55
H)
23
I)
-85
J)
-11
Closure
 Review objective:
 Today, I will add and subtract integers using three different
methods.
 Which method is the best?
 Why?
Finding a difference!
What is the difference between 48 in. and 29 in.?
48
-29
19 in.
?
29
48
What about this difference?
A hiker climbed from -37 ft. to 214 ft. How far did she
climb in total?
+214
+37
-37
214
+37
251 ft.
0
214
Practice!
1.
In Utah, the high at noon would be 55˚ F then
drop to 11 ˚ F by 9 pm. What is the difference in
temperature?
Start: 11
End: 55
Difference: 44˚ F
2.
After our first sushi roll, our bill was $14. After 13
rolls, our bill was $192. How much did the bill
change by?
Start: 14
End: 192
Difference: $178
3.
When sick, Angela’s temperature was 101.8˚ F .
The next day, her temperature was 99.6. How
much did her temperature drop?
Start: 99.6 End: 101.8 Difference: 2.2˚ F
More Practice
4. If you move a point on a number line from -9 to
10, how many units did you move it?
Start: -9
End : 10
Difference: 19 u
5. Before school, the temperature was -4 ˚ F. After
school, the temperature was 23 ˚ F. What is the
difference?
Start: -4
End : 23
Difference: 27 ˚F
6.
Tony’s account was $303 before he went
shopping. After, he saw that his account was
$ - 16. how much money did he spend?
Start: -16
End : 303
Difference: $319