1. 7.8 Adding Positive and Negative Numbers Miss Hepner

2. Math Message

3. Mental Math Reflexes Use, or = to compare numbers 1.-5 and -7 2.2.5 and -1 3.- 8/4 and -2

4. Adding Positive and Negative Numbers Objective: To develop rules for adding positive and negative numbers Lesson Essential Question: How do I add positive and negative numbers and what strategy can I use?

5. 3 Strategies Today we will learn 3 different strategies to add positive and negative numbers. You choose the strategy that works best for you! The three strategies include: 1. Pair and cancel (using + and – tokens) 2. Number line method 3. Subtract and Highest Sign (team and battle)

6. How do I add positive and negative numbers? Strategy #1 -9 + 5 Pair and Cancel Method: Take nine negative tokens and five positive tokens

7. How do I add positive and negative numbers? Strategy #1 -9 + 5 Pair a negative token with a positive token

8. How do I add positive and negative numbers? -9 + 5 The paired tokens cancel each other out! Count the left over tokens and there is your answer.

9. How do I add positive and negative numbers? -9 + 5 = -4

10. Let’s try another example using Strategy #1 -3 + 6 Pair and Cancel Method: Take nine negative tokens and five positive tokens

11. -3 + 6 Pair a negative token with a positive token Count your left over tokens and that is your answer.

12. How do I add positive and negative numbers? -3 + 6 = 3

13. Another way to look at it: -9 + 5 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 Number Line Method

14. Another way to look at it: -9 + 5 = -4 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1

15. Strategy #2- Number Line -5 + -3 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 Number Line Method

16. Strategy #2- Number Line -5 + -3 = -8 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1

17. Another way to think about it… Subtract the two number and take the sign of the larger: -9 + 5 = 9 – 5 = 4 (take the sign of the larger) Answer = -4 Subtract and Highest Sign Method

18. Pair and Cancel Method -3 + 7 Take three negative tokens and seven positive tokens

19. How do I add positive and negative numbers? -3 + 7 Pair a negative token with a positive token

20. How do I add positive and negative numbers? -3 + 7 The paired tokens cancel each other out! Count the left over tokens and there is your answer.

21. How do I add positive and negative numbers? -3 + 7 = 4

22. Number Line Method -3 + 7 -3 -2 -1 0 1 2 3 4 5 6 7

23. Another way to look at it: -3 + 7 = 4 -3 -2 -1 0 1 2 3 4 5 6 7

24. Subtract and Highest Sign Method Subtract the two number and take the sign of the larger: -3 + 7 = -3 + 7 = 4 (take the sign of the larger) Answer = 4

25. Practice: 7 – 10 -4 + 12 9 – 15 -3 + 8 -6x + 2x