1. How are -11 + 9 and 9 + (-11) related?

2. In this lesson you will learn to demonstrate the commutative property of addition by using a number line.

3. Let’s Review What’s an integer? Integers include positive and negative whole numbers as well as 0....-3, -2, -1, 0, 1, 2, 3... Non-Examples:

4. Positive NumbersNegative Numbers Increasing in Value Decreasing in Value What’s a number line?

5. Let’s Review What’s addition? Addition is the process of joining two groups. 7 + 11 = 18 addend sum

6. Let’s Review A Common Mistake Re-ordering the addends in an addition problem without re-ordering the signs. + 9 -11 + 9 11 - Commutative Property

7. Let’s Review A Common Mistake + 9 -11 + 9 11 - = - Re-ordering the addends in an addition problem without re-ordering the signs.

8. Let’s Review A Common Mistake + 9 -11 + 9 -11 ( ) Re-ordering the addends in an addition problem without re-ordering the signs.

9. Let’s Review A Common Mistake + 9 -11 = + 9 ( ) Commutative Property Re-ordering the addends in an addition problem without re-ordering the signs.

10. Let’s Review Core Lesson 62 8 62 8 6 + 2 2 + 6 Commutative Property

11. Let’s Review Core Lesson -4-3 -4 + (-3) -3 + (-4) -7 -4-3 -7 Commutative Property

12. Let’s Review Core Lesson 9 -11 9 + (-11) -11 + 9 -2 -11 9 -2 Commutative Property

13. In this lesson you learned to demonstrate the commutative property of addition by using a number line.

14. Let’s Review Guided Practice 14 + (-9) -9 + 14 Show that 14 + (-9) is equal to -9 + 14.

15. Let’s Review Guided Practice -6 + (-8) -8 + (-6) Demonstrate that -6 + (-8) has the same value as -8 + (-6).

16. Let’s Review Extension Activities Use Cuisenaire rods to represent integers 1-10. Model addition problems that show the commutative property by laying the rods on a number line. These rods represent 8 + (-5) and -5 + 8. Both sums are positive 3!

17. Let’s Review Extension Activities The commutative property of addition is sometimes called the order property. Use the commutative property to rearrange these addition expressions so you can add them mentally. (Hint: Try to make sets of ten.) A) -15 + 28 + (-5) B) -99 + 17 + 3 + (-1) C) 74 + 12 + (-4) + 5

18. Let’s Review Extension Activities Partner Game: First partner writes an integer addition problem for the second partner. The first partner solves the original problem on her own paper. The second partner switches addends using the commutative property and solves the equivalent problem on his paper. Both partners compare their answers.

19. Let’s Review Quick Quiz Which expression has the same value as -13 + 7? A) 7 + (-13) B) 13 + (-7) C) -13 + (-7) D) -7 + 13 Which expression has the same sum as -9 and -2? A) 2 + 9 B) 2 + (-9) C) 9 + 2 D) -9 + (-2