How Much Per Gallon?
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!!!
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
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
8 ounces in a cup = __8__
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
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
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
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
5. Dish soap
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.
some other liquids you could use for your 10:
Bottled iced tea
such as Evian
NOT TO DRINK,
but here are other liquids:
(from the office supply store)
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.
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
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?!?