1. Adding/Subtracting Integers
Objective: students will learn how to apply the rules for adding and subtracting integers. They will also demonstrate on a number line how to use addition.

2. Adding with number lines
Use number line:
Positive move right
Negative move left
Ex: Use a number line to express

3. Student Examples Use a number line to solve the following. -1 + -8

4. Adding Integers w/o number line
Helpful hints (when adding)
Same sign (4 + 5): add numbers use common sign.
4 + 5 = 9, common sign + answer is positive.
Different sign (-6 + 7): subtract numbers; use bigger numbers sign.
7 – 6 = 1, bigger sign +, answer is 1
Opposites: (5 + -5): add number and it’s opposite get zero.
Known as Additive inverse property

5. Solve-t

6. Subtracting Integers
To subtract integers, change subtraction to addition. Then change the number behind to it’s opposite.
Refer to poster!!!
Examples:
2 – 8
3 – (-10)

7. Student Examples -2 – 3 -1 – (-14) 70 – 20 -10 – 52 -70 – (-70)
63 – (-23)

8. Examples t/st -46 + 26 -50 – (-20) -11 - 60 -10 + (-8) 80 + (-80)
What is the above problem also called?

9. Adding/subtracting two or more - t
52 + (-20) - (-26)
(-30)

10. Student Examples -20 - 36 + (-74) 26 + 55 + -45 -56 + -20 + 36
– (-78)

11. Variable expressions - t
Use a = 5 and b = -10 to solve expressions
a + -8
32 + b
a - b
b + 9
23 - a

12. Student Examples Evaluate when a = -4 and b = 5 a + b 54 + a

13. Problem Solving-t
A football team gained 12 yards on a play. It then lost 10 yards on the next play. What was the total change of yardage for the team?

14. Problem Solving-st
Suppose you deposited $25 into your checking account and wrote a check for $38. What was left in your account?

15. Wrap-up Questions / Comments Hw:
Objective: students will learn how to apply the rules for adding integers. They will also demonstrate on a number line how to use addition.