Money:

How Much Per Gallon?

 

            Today's Snack: If you're doing today's treat on your own, look out. This is a time to have some friends around! We're going to focus on the unit of measurement called a gallon.

A lot of people buy milk by the half-gallon. So take an empty half-gallon milk container, and wash it out very, very well.

Now fill it with cold water. Your goal is to drink that half-gallon of water - TWICE! - before the end of this exercise.

If you're alone, you'll have to drink it yourself. Gulp! Literally!

If you're in a group, you're lucky. You can all split up the gallon and drink it together. Pour servings into a cup as you go.

Afterwards, make sure there's a restroom handy!

If a gallon of water isn't enough to fill your tummy, add a small apple as a snack, too. Only be advised: it's more of the same! An apple is mostly WATER!!! AAAIIIEEE!!!

 

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Supplies:

5 liquid items that are beverages or for household use,

with pricetags and ounces listed (for gasoline, just check at the pump; don't bring gasoline inside!!!)

 

(suggested items are listed below; if the prices aren't evident,

you can call the local grocery store or hardware store for a price check)

 

2 pieces of paper per student, colored markers and a pencil

 

One calculator per student (unless you'd prefer paper and pencil computation)

 

2 well-washed empty half-gallon milk containers (one for snack, above)

 

Funnel | Permanent marker | One-cup measure

 

Access to water

 

 

            Everybody's complaining about the price of gas. Do you know how much gas costs per gallon at a gas station near you today? If you don't know, give them a call and find out.

 

Ooh! Seems like a lot, eh? But let's put it into perspective. Let's figure out how much some other things cost, if you were purchasing them by the gallon.

 

First, let's review the basic units of liquid measurement:

 

8 ounces in a cup = __8__ ounces

 

2 cups in a pint = _____ ounces

 

2 pints in a quart = ______ ounces

 

4 quarts in a gallon = _____ ounces

 

Let's get a better idea of the quantities that these measurements represent. Measure one cup of water and pour it through the funnel into the empty half-gallon container. Mark the line with the permanent marker: 1 CUP. Now pour in another cup of water through the funnel. Mark that line: 1 PINT. Continue adding cups of water until you can mark 1 QUART, and then 2 QUARTS / 1 HALF-GALLON.

 

Are you surprised by how much liquid there is in a gallon?

 

Let's also do a little math to fill in those blanks about ounces up above. Since we're going to be working with ounces, it's important to recognize how many ounces there are in each of these measurements.

 

If there are 8 ounces in a cup, and two cups in a pint, how many ounces in a pint? (8 ounces x 2 cups = 16 ounces in a pint)

 

A quart has two pints, so how many ounces in a quart? (16 x 2 = 32 ounces)

 

How many pints are there in a gallon? Well, there are two pints in a quart, and four quarts in a gallon. So there must be 2 pints x 4 quarts = 8 pints in a gallon.

 

If there are 16 ounces in a pint, and we've given you how many pints there are in a quart and how many quarts there are in a gallon, how many ounces are there in a gallon? (16 ounces in a pint x 8 pints in a gallon = 128 ounces in a gallon) (Or, to make it easier, once you know that there are 32 ounces in a quart and four quarts to a gallon, multiply 32 x 4 = 128 ounces in a gallon)

 

Now comes the fun part. Guess which of the 10 liquids you have gathered is going to turn out to be the most expensive? Let's make a chart, and figure out how close you came. You might want to color-code the columns so that you can keep the numbers straight.

 

List the names of the liquids down the left-hand side of a piece of paper. Then go back and rate them from 1 to 10, 1 being the one that you think will be the most expensive per gallon, all the way down to the liquid that you think will end up the cheapest per gallon. Leave a blank for the REAL ranking, which we won't know 'til we've done the activity.

 

Make columns in the middle where you list how many ounces there are in each liquid and how much that container costs, and a right-hand column for the cost per gallon.

 

Here's an example with the five items listed below. Rank them according to your guess of which one is the most expensive per gallon (rank-guess #1) all the way to which of the five is the least expensive per gallon (rank-guess #5). Then figure out the price per ounce, and by multiplying that times 128, figure out how much it costs per gallon. Then fill in the actual ranks of the five liquid products.

 

In our example, we'll fill in the price per gallon for you (the last category, PPG, means "Price Per Gallon). For the bottle of Diet Snapple iced tea drink, we divided the $1.29 price by the 16 ounces in the bottle. We came up with $.080625 cents per ounce. Multiplying that times 128 ounces, we came up with the $10.32 price per gallon for the Diet Snapple drink.

 

Now you figure out the Price Per Gallon for the other four liquid products you selected:

 

LIQUID PRODUCT  RANK-GUESS      RANK-ACTUAL # OZ / PRICE      PPG

 

1. Diet Snapple           ________             _______         16 oz / $1.29     $10.32

 

2. Milk

 

3. Glue

 

4. Gasoline

 

5. Dish soap

 

(etc.)

 

 

If you have a quantity that is not an even pint or quarter, you will have to divide the price by the number of ounces to find the price per ounce, and then multiply that price per ounce times the number of ounces in a gallon to come up with a price per gallon.

 

Here are some other liquids you could use for your 10:

Soda pop

Bottled iced tea
Gatorade

Juice

Bottled water, such as Evian

NOT TO DRINK, but here are other liquids:
 
Brake fluid 
Vick's Nyquil 
Pepto Bismol

Whiteout ink (from the office supply store) 
Scope mouthwash

           

            You may have completely different items for your comparison. Just be sure that, for each, you know how many ounces are in the container, and how much the container cost. Then you can figure out the price per ounce, and ultimately the price per gallon.

 

Have fun!

 

            When you are finished calculating, take some time to reflect. How close were your rankings?

 

Why do you think you were close, or, if you were 'way off, what threw you off?

 

Does this change your mind about how much gas costs?

 

How about how much other things cost?

 

Do you think this activity will make you a little less wasteful?

 

            Speaking of . . . waste . . . has that gallon of water kicked in yet, and do you need to visit the restroom?!?

 

Happy kidneys!