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Do Now 8/23

Do Now 8/23. Please have your math journals out. I am checking them today. 9 + (-2) = _____ (-8) + _____= -10 11 + _____= -2 Give me 5 non-examples of integers. Fooling the Subtraction Guardian. August 23, 2013. Learning Goal.

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Do Now 8/23

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  1. Do Now 8/23 Please have your math journals out. I am checking them today. • 9 + (-2) = _____ • (-8) + _____= -10 • 11 + _____= -2 • Give me 5 non-examples of integers.

  2. Fooling the Subtraction Guardian August 23, 2013

  3. Learning Goal • I can subtract integers by adding the opposite and explain how it works.

  4. Vocabulary: “Additive Inverse” • Additive Inverse – math word for opposites. • adds to 0. • Example: -1 + 1= 0 • have the same absolute value • Example: |-1| = 1 |1|= 1 “1 is the additive inverse of -1.”

  5. Yesterday • We went to Addition Mountain • Can you use subtraction problems on Addition Mountain?

  6. Only Addition Problems on Addition Mountain • This would be allowed on Addition Mountain: 3 + (-2) = 1 3 + 2 = 5 -2 + 5 = 3 This would not be allowed on Addition Mountain 5 – 8 = -3 4 – (-1) = 3 -9 – 6 = - 15

  7. The Subtraction Guardian • The Subtraction Guardian guards Addition Mountain. • He checks to see if you are an addition problem, or a subtraction problem.

  8. But Subtraction can Transform itself! How? Subtraction is the same as adding the opposite. (Keep Change Opposite)

  9. Can I go to Addition Mountain? 5 + (-3) = (-3) + (-1) = 1 – (-2) = 9 – 4 = Yes Yes No No

  10. Subtracting is Adding the Opposite • 5 – (-3) = • 5 + (-3) = • -5 – (-3) = • -5 + 3 =

  11. What about this? -5 + 3 – (-2) =

  12. Exit Ticket • -5 and 5 are additive __________. • -5 – (-3) + (-1) = ____

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