Adding integers with the same sign using models

Lesson # 2: Adding integers (with the same sign)

Integers1.gif

Objectives

  1. Understand how to use models to add integers with the same sign
  2. Evaluate integer addition problems using mental math
  3. Develop methods for using integer tiles
  4. Develop real life situations that model expressions

Warm-Up

  • State the definition of an integer and give three examples.
  • Use integer tiles to add the following integers:
  1. - 8 + 3
  2. -6 + 6
  3. 13 + -8

Answers to Warm-Up

Adding integers with the same (negative) sign

We want to use integer tiles again to add integers that have the same sign. So, both numbers are negative or both numbers are positive.

Let’s start with adding two negative numbers. Use your integer tiles to represent the expression...

-8 + -6 - 8 + -6.jpg


Steps

  • 1. Arrange your integer tiles.

Use your integer tiles to represent:

  • 4. -4 + -5


Stopthink1.jpg

When you are adding numbers with the same sign, what are you really doing? Answer

Can you think of a real life situation with your bank account that can represent adding to negative integers? Share here

Adding Integers with the same (positive) sign

You already know how to do this!

  • 6. ) 4 + 8 = 12
  • 7. ) 19 + 25= 44
  • 8. ) 25 + 18 + 30 = 73


Here are the “rules” for adding integers with the same or different signs. Don’t memorize them! These should be used to help you explain your method.


  • Let's use some mental math! Solve the following problems using mental math...
  1. -8 + -9
  2. -15 + -6
  3. 50 + 36
  4. -200 + -50

Answers to mental math problems

Assessment

Try out these websites to practice all of your new skills for adding integers with the same and different signs.

  • [1]
  • [2] <-- This website uses models to help you add!

Share one thing you have learned on this wiki page from Lesson # 2.

Good job gold ribbon.png

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