HOT AIR BALLOON INTEGERS:

ADDING AND SUBTRACTING

By: Allison Coomes

Hot air balloons move up off the ground using hot air. Using a number line, we can determine that the puffs of air are moving the balloon in an upward, or positive, direction.

The balloons use weights, such as sand bags, to help bring them down to the ground. Since this causes the balloon to move down the number line, the sand bags represent negative numbers.

So, if our balloon started at ground level (0) and it received 4 puffs of air, where is it on the number line?

0+4=4

Now, let's add some negative numbers, or sand bags. We were on 4 on our number line. Let's add 3 sand bags. Since the sand bags represent negative numbers, we add a -3.

4+(-3)=1

We can also write this as: 4-3=1

Now what do you think will happen when we subtract positive and negative integers? Will it be the same as adding? Please respond below.

Subtracting positive integers will just be review for you. For example:

4-2=2 and 10-4=6

Subtracting negative integers is a little different. Look at the examples below.

4-(-1) is the same as 4+1.

Both equations equal 5 because two negative signs -(-) make a positive or + sign.

This means that you change the -(-1) to a +1.

Ok, let's look at some more examples.

15-2=13

but 15-(-2)=15+2 which equals 17.

What if we tried -10-2?

We would start at -10 on the number line and move down 2 spaces to land on -12.

One last example before you try this on your own.

-8+2-(-5)=?

-8+2=-6 and -6-(-5) is the same as -6+5 which equals -1.

Now it's your turn!

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**GoAnimate.com**: Integers by AllisonCoomes

Resources

1. http://www.balloonridesoversyracuse.com/images/lta2.jpg

2. http://www.deshow.net/d/file/sports/2008-10/hot-air-balloon-campaign-2.jpg

3. http://www.pearsoned.ca/highered/divisions/economics/images/Fg_-03.gif

4. http://www.baitali.com/photo/submenues/HotAirBalloon_20090212113000.jpg

5. http://www.game-reserve.com/images/wildlife/primates_other/chimp_junior_da.jpg

6. http://www.lifefocuspro.com/wp-content/uploads/2007/02/1935703.jpg