The Metric System
The Metric System
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All scientific measurements are made using
the Metric System.
It is also called the SI System
(La Systeme International d’Unites)
The Unites States is the only major country
that does not use this system.
Very Easy To Use
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Based on multiples of 10 (10 and 100 and
1,000 and 10,000 … etc.)
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Much easier conversions because of the 10’s
• Think of how hard it is to work with conversions in
our system! How many inches in a foot? Feet in a
mile? Ounces in a pound?
Very Easy To Use

It’s a decimal system… Can you think of a
system we use every day that is a decimal
system?
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How many pennies in a dime? How many
dimes in a dollar? How many $1 dollar bills are
in a $10? How many $10 dollar bills in $100?
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Each measurement has a base unit
and a prefix
Base unit
• the last name of a measurement (tells
which family you belong to) and helps
you determine what we are measuring
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Prefix
• the first name of a measurement
(separates you from the other members
of your family) and helps you determine
the size of what we are measuring
Metric Base Units
What we’re measuring
Metric Base Unit
Length
Mass
Volume
(how long it is)
Density
(how much matter in a given
g/L (for liquids)
amount of space)
g/m3 (for solids)
(how much heat it has)
°Celsius
second
Temp.
Time
(how much matter is in it)
(how much space it takes up)
(how long it takes)
meter
gram
liter (for liquids)
meter3 (for solids)
How Do We Measure Them?
Length
Temperature
Volume
Time
Mass
Length
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The length, width, or height of an
object tells us the distance between
two points on that object
We use a ruler, meter stick, or tape
measure to find this measurement in
meters
Mass
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The mass is the amount of matter in an
object and won’t change.
We use a triple beam balance to find the
mass of an object in grams.
Mass vs. Weight
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Mass is NOT the same as weight!
The weight of something is the amount of
gravity acting on an object and will
change if you go somewhere with more or
less gravity.
Volume
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For easy-to-measure solids (like a tissue
box), we use a ruler to find the volume in
cubic meters (m3).
Volume (m3) = Length x Width x Height
Volume
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The volume is the amount of space an
object takes up.
For liquids or oddly-shaped solids, we use
a graduated cylinder or beaker to find the
volume in liters (or mL).
Volume
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The surface of the liquid might look
slightly curved.
This curve is called the meniscus and we
read the amount from the lowest point of
the meniscus.
Density
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Density is the amount of matter
(mass) in a given space (volume)
Density = Mass (g) ÷ Volume (mL or m3)
For example, water’s density is 1 g/mL
which means that there is 1 gram of
matter in every mL of water.
Density
Think of it like a suitcase…
the more clothes you try to fit in a
suitcase, the more packed it gets.
More packed = More dense
Density
When you compare the density of two
or more objects, the denser objects
will sink below the less dense objects.
Sink or Float?
Density
REMEMBER: Denser objects sink below less
dense objects!
• Number your paper 1 – 4
• Order the following objects from least
dense (#1) to most dense (#4):
• Water (blue), Syrup, Rubbing Alcohol
(red), and Vegetable Oil
The length of the yellow line
in meters (there will be a
decimal) is _______ m
Use the triple beam balance to find
the mass of a football in grams?
Use the meniscus (lowest point of the water’s surface)
to find the volume of the water (there will be a
decimal). The volume is about _______ L.
Metric Prefixes
kilo
hecto
deka
1000 base units
100 base units
10 base units
BASE UNIT
1
deci
1/10 (0.1) of a base unit
centi
1/100 (0.01) of a base unit
milli
1/1000 (0.001) of a base unit
Moving the Decimal for Length
Larger Units,
Smaller Number
Smaller Units,
Larger Number
Base Unit
kilo
(km)
Hecto
(hm)
Deka
(dka)
METER
(m)
Deci
(dm)
Centi
(cm)
Milli
(mm)
Moving the Decimal for Mass
Larger Units,
Smaller Number
Smaller Units,
Larger Number
Base Unit
kilo
(kg)
Hecto
(hg)
Deka
(dkg)
GRAM
(g)
Deci
(dg)
Centi
(cg)
Milli
(mg)
Moving the Decimal for Volume
Larger Units,
Smaller Number
Smaller Units,
Larger Number
Base Unit
kilo
(kL)
Hecto
(hL)
Deka
(dkL)
LITER
(L)
Deci
(dL)
Centi
(cL)
Milli
(mL)