7th Grade Section
WME@Kimpton Middle

Understanding Negative Integers II

Jar and CookiesTo explain negative integers in a different way, let us use the cookies and cookie monster model:

  • A cookie represents the integer 1, two cookies 2, and so on.
  • A cookie monster represents −1, two monsters −2, and so on.
  • A monster with a cookie represents 1 − 1 or zero.
  • Putting cookies or monsters in the jar models additon.
  • Removing cookies or monsters from the jar models Subtraction.

Let's see how this model works.

8 + (−3) means: The cookie jar starts with 8 cookies, now add 3 cookie monsters.

5 − (−3) means: The cookie jar starts with 5 cookies, now remove 3 cookie monsters.

This tool helps you visualize what we mean.

Do 8 + (− 3) this way:

  1. First add 8 cookies in the above grid (the cookie jar).
  2. Now add cookie monsters on top of cookies. How many cookie monsters do you need to put in?
  3. What is the answer? (Hint: how many uneaten cookies remain?).

Next, do 5 − (−2) this way:

  1. Observe we have 5 cookies and 3 satisfied monsters in the grid already.
  2. Now remove cookie monsters. How many cookie monsters do you need to remove?
  3. What is the answer for 5 − (−2)?

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