Name: ___________________
Introduction to the Metric System
Why can’t I just use inches and feet? Mr. Bell you are drawlin’!
Why we use Metric Units…
Metric units are very nice to work with, since they are all multiples of ten (or a hundred, or one-tenth, etc) of
each other. You can convert between the various different sizes by merely moving the decimal point the
correct number of places. But when we use the English system, converting between units is a pain in the...Let
me show you.
Let’s do a problem the English way (the old way). PJ is trying to get husky for football so he runs 5 miles a day
before school. Let’s assume that he needs to know how many inches that is for science class (I am not sure
why he would need to know this, but let’s just assume that Mr. Bell likes to make things extra hard on his
students…again, he’s drawlin’) To do this you would first have to figure out how many feet are in a mile, which
is 5280ft = 1mile (where the frog that number came from is anyone’s guess, but have fun memorizing that!)
Then you have to multiple 5280 x 5miles to get the number of feet PJ runs. This equals, 26,400 feet. Then you
would have to take that number and multiple it by 12 because there are 12 inches in a foot. You get a final
answer of 316,800 inches run each morning by PJ to get extra husky. Here is the math all at once…
5,280 x 5 = 26, 400 x 12 inches = 316, 800inches,
Try that without a calculator.
Now let’s do this the metric way, the easier way (maybe Mr. Bell is not so drawin’ afterall) Note: 5 miles = 8
kilometers. And instead of inches, let’s use centimeters.
Since there are 1000 meters in every kilometer, and there are 100 centimeters in every meter, you can just
take the 8km and multiple it by 1000, and then by 100 (which is the same as adding 5 zeros to the 8) Bet you
don’t need a calculator for that! Here is the math all at once…
8 + 5 zeros = 800,000cm,
Wow, that math problem is crazy…
So which do you like better? The English system? Of the Metric System? Hopefully you agree adding zeros is
better than long division and multiplication, and you are starting to realize that the metric system will actually
make your life a lot easier! So here are the basics….
Base Units of the Metric System…
The basic metric units are meters(m) for length, grams(g) for mass or weight (also known as g-g-g Gunits…corny yes, but you will now never forget what the base unit is for mass because of Mr. Bell’s corny
jokes…so now what), and liters(l) for volume.
And the different units convert into one another rather nicely, with one milliliter (liquid volume) equaling one
cubic centimeter(solid volume) (the "cc’s" of medical shows on television) and one gram being the weight of
one cc of water. So volume, mass, length are connected.
Convert Between Metric Units…
There are many metric-unit prefixes, but the usual ones required in school are these: kilo-, hecto-, deka-,
deci-, centi-, and milli-. To convert between the various prefixes, and thus the variously-sized units, you just
move up and down this list of prefixes, moving the decimal point as you go. In our class we will only use kilo-,
deci-, centi-, and milli-, but you need to know the order of all 6 prefixes to know how many decimal places to
move.
To remember the prefixes in order, you can use the following sentences:
King Henry Doesn't [Usually] Drink Chocolate Milk
The first letters of the words stand for the prefixes, with "Usually" in the middle standing for the "unit", being
meters, grams, or liters based on what you are measuring/converting at the time. Many memory phrases omit
the "Usually", and consequently students forget where the basic unit goes, messing up their conversions.
Leave the "Usually" in there so you can keep things straight:
kilo- hecto- deka- [unit] deci- centi- milliSince each step is ten times or one-tenth as much as the step on either side, we have:
1 km = 10 hectometers = 100 dekameters = 1000 meters = 10,000 decimeters = 100,000 centimeters =
1,000,000mm, All you are doing is multiplying by 10 for each time you move from bigger to smaller units.
Alternatively, we have:
1 milliliter = 0.1 centiliters = 0.01 deciliters = 0.001 liters = 0.000 1 dekaliters = 0.000 01 hectoliters = 0.000 001
kiloliters All you are doing is dividing by 10 each time you move from small units to bigger units.
The point here is that you move from one prefix to another by moving the decimal point one place, filling in, as
necessary, with zeroes. To move to a smaller unit (a unit with a prefix some number of places further to the
right in the listing), you move the decimal place to the right that same number of places, and vice versa.
Together with the prefix sentence ("King Henry..."), this makes conversion between the different metric sizes
very simple.
Example 1: Convert 12.54 kilometers to centimeters.
How many jumps is it from "kilo-" to "centi-"? Five, to the right.
So I move the decimal point five places to the right, filling in the extra space with zeroes:
You don't have to make a loopy arrow like I did, but the loops help you keep track of the steps that you're
counting, and make it really easy to see where to add the zeroes, if you need to. In this case, after moving the
decimal point and adding the zeroes, I get …12.54km = 1,254,000cm
Example 2: Convert 457 mL to hL.
How many jumps is it from "milli-" to "hecto-"? Five, to the left.
So I move the decimal point five places to the left, filling in the empty spots after the decimal point with zeroes:
Then my answer is: 457ml = 0.00457hl (even though we won’t really use hectometers)
That's all there is to metric conversions. As long as you keep the prefixes straight and remember where in the sequence
the "units" name goes, you'll be fine. Just count the number of jumps and note the direction; then move the decimal point
the same direction and the same number of places. Then fill in any zeros and you are golden.
Part I: Whatcha’ know about the Metric System?
1) Make a Mnemonic for the Metric System! This is a memory device to help you remember the order of the prefixes.
Create a sentence using words that start with the first letter of each prefixes.
KHDUDCM-
2) What are the 3 base units for the metric system?
Mass: _______________
Volume: ________________
Length: _________________
3) Why is the metric system so much easier than the English System?
4) How are mililiters and cubic centimeters and water all related?
5) When doing a metric conversion problem, does the base unit matter, or are you only concerned with the prefix. Explain
yourself.
6) When doing a metric conversion problem, how do you know whether to move the decimal point to the left or the right?
Part II. Practice Metric Conversions
1
256 m = __________ cm
15
9,824 cm = __________ m
2
97.25 cm = __________ mm
16
74.21 cm = __________ km
3
952 g = __________ mg
17
0.254 g = __________ kg
4
0.574 m = __________ cm
18
96 mm = __________ km
5
5.287 l = __________ ml
19
12.5 cm = __________ m
6
785.3 km = __________ m
20
0.85 ml = __________ l
7
84.363 km = __________ cm
21
36.52 mg = __________ g
8
872 km = __________ mm
22
14.72 kg = __________ mg
9
95,824 cm = _________ mm
23
0.0035 mm = __________ km
10
8.26 kl = __________ ml
24
0.134 m = __________ km
11
36 mm = __________ cm
25
25 mm = __________ cm
12
857 cm = __________ mm
26
2.5 cm3 = __________ mL
27
45.23 L = __________ mL
13
8.52 mg = __________ g
28
27.32 mm = __________ m
14
975 ml = __________ cm3 (look in reading)
29
0.023 cc = __________ L (look in reading)