Subtracting Integers! Ms. Buffo 7th grade math

Warm up: A popular family owned diner is famous for their soup. The chef does not cook his soup in a microwave or on the stove. Instead, he uses hot and cold cubes to get the perfect temperature. The chef wants to change the temperature without adding any more hot or cold cubes. To do this, he simply uses a large ladle to scoop out a hot or a cold cube. To make the soup warmer, he would scoop out at _________ cube. To make the soup cooler, he would scoop out a ________ cube.

Think about it…… What operation is it when you are taking out the cubes? What would you call a hot and a cold cube together? With your shoulder partner, figure out how you can make the soup hotter with and without taking cubes out, or make it cooler with or without taking cubes out. Next, come up with a rule for subtracting integers.

To subtract integers, you _____ the ________ of the ___ ________! To summarize: To subtract integers, you _____ the ________ of the ___ ________! Subtracting a negative is the same as ________ a ___________________.

Then follow your adding integers rules! When subtracting integers there is a trick that I use that helps you get the correct answer: L. C. O. Leave Change Opposite (1st # - to + of 2nd # ) Then follow your adding integers rules! Its THAT easy!

L.C.O. Lets practice as a class! 9 – (-2) = -4 – 3 =

Using 2-sided counters: You can use 2 sided counters to help you solve as well. Set up your counters as the problem states. Leave your first group alone Change subtraction to addition. Flip your 2nd number (whether its positive or negative) to the opposite and follow the adding integer rules. Example: 8 – (-3) = -5 – 9 =

Lets practice! -3 – (-2) = 8 – 17 = -9 – 3 = 7 – (-4) = 5 – 23 = -3 – (-7) =