The Metric System (The International System of Units)
Scientists use the metric system when making observations and taking measurements. The
metric system is a form of measurement that scientists around the world use. This form of
measurement is also known as the International System of Units, or (“SI”). This measurement
system allows scientists to be as precise as possible when performing lab experiments. In
science, everything must be exact. This enables others to perform particular experiments in the
same manner as others performed them.
T The metric system uses units that can be converted (changed) from one unit to
another. T another. The metric system allows inches to be converted to meters. The United
States
States uses feet and inches to measure things. This is not the metric system.
You canus
use a
measuring
tape to
measure
meters.
The metric system uses abbreviations, or shorter letters, words, or phrases when
referrring to measurements. The metric system uses meters (m) to measure
distances. The smallest units are called millimeters (mm). They are the closest and
smallest lines on a meter stick or measuring tape. Ten millimeters make up one
centimeter (cm). Ten centimeters make up one decimeter (dm), and ten decimeters make up one
meter (m). The units in the metric system increase by tens.
To convert centimeters to millimeters, multiply by ten. To convert 97 centimeters to millimeters,
multiply 97 by 10 for the sum of 970 millimeters (97x10 = 970 mm.) Because millimeters are
smaller than centimeters, divide by ten to convert millimeters to centimeters. 97 millmeters are
equal to 9.7 centimeters (97mm x 10 = 9.7). Simple phrases help students remember the units
for meters.
King Henry’s Dad
Made
Disgusting Chocolate Milk
Kilo- Hecto- Deka- Meters Deci-
Centi-
Milli-
The metric system measures mass and volume. Mass is the measure of the amount of matter
in an object and is measured in grams (g).
Matter is anything that has mass and volume, or takes up space. This is almost everything,
including the air that is breathed, a desk, and of course you. Volume is the amount of space
that something takes up and is measured in liters (l). Things that are not considered matter,
such as ideas, heat, light, and thoughts do not have mass or volume.
Examples of mass and volume:
Example 1:
Weight is the pull of gravity on the body. Weight can change based on the
amount of gr amount of gravity. Astronauts in space weigh almost nothing because there is
little gravity I little gravity in space, but the astronaut’s mass has not changed. A weight scale
is used to m is used to measure weight, but to measure the mass of an astronaut a balance
scale must b scale must be used. When stepping on a scale in space, gravity is not pushing
graduated
down very h very hard and the astronaut would appear weightless. If a balance scale is used,
cylinders
gravity would gravity would push down on both sides of the balance evenly and the balance
scale would scale would read the same as if it were on Earth. The mass did not change.
A simple
balance
Example 2:
A triple
beam balance
Soda is purchased by the volume. Soda bottles hold 2 liters of soda. Liquid is
measured using liters.
Here are 2-liter bottles of soda that
one sees in a store.
Example 3:
A box takes up space. The space or volume an object takes is measured by
measuring the height, length, and width of the box, then multiplying the
measurements. If a box is 3 cm high, 6 cm long, and 4 cm wide, multiply 3 cm x 6
cm x 4 cm and the answer will be 72 cm3. The unit “cm3” is
centimeters cubed which is equal to a milliliter (mL). 1mL = 1cm3.
The chart below shows how many of each unit one has if one has just one of the
standard units. For example 1 meter = 1000 millimeters.
Prefixes:
distance in meters(m)
mass in grams(g)
volume in liters(l)
kilo.001km
.001kg
.001kl
hecto.01 hm
.01 hg
.01 hl
deka.1 dam
.1 dag
.1 dal
unit
1m
1g
1l
deci- centi10 dam 100 cm
10 dag 100 cg
10 dal 100 cl
milli1,000mm
1,000 mg
1,000 ml
Some easy conversion rules: There are 37.5 meters. Convert this to kilometers by moving
the decimal place to the left three spaces or the number of units away from meters. See
below:
Prefixes:
kilo-
hecto-
deka-
unit
37.5 m
3.75 dam
.375 hm
.0375 km
*
**
To convert 37.5 to .0375 kilometers move the decimal three places to the left.
To convert 37.5 meters to millimeters, move the decimal three places to the right.
deci-
centi- milli-
I.
The Metric System is a standard system of measurement used
everywhere in the world.
A. The Metric System is also known as the International System of
Units or SI units.
B. This system was developed so scientists everywhere in the
world could always use the same units to perform experiments.
II.
Be Precise—this means measurements should be made as closely as
possible to the correct number every time measurements are made. Never
guess when measuring. An incorrect measurement can ruin an entire
experiment.
III.
UNITS – different types of measurement are used for different types of
units.
A. Mass – is measured using grams also written as g.
The tool used to measure mass is the balance scale.
B. Volume – is measured using liters also written as l.
1. The tool used to measure volume is the graduated cylinder.
2. Multiplying their length, width, and height can solve 3-D objects.
C. Distance – is measured in meters also written as m.
The tool used to measure distance is a measuring tape or a ruler.
IV.
Conversion – sometimes it is necessary to use bigger or smaller units. The
size of the units change when they are converted.
A. The metric system was designed on a scale of ten.
B. The scale of ten means that the units of the metric system can easily be
converted by moving the decimal point to the left to make a bigger unit
and to the right to make a smaller unit.
Prefixes:
kilodistance in meters(m) .001km
mass in grams(g)
.001kg
volume in liters(l)
.001kl
hecto.01 hm
.01 hg
.01 hl
deka.1 dam
.1 dag
.1 dal
unit
1m
1g
1l
deci10 dam
10 dag
10 dal
centi100 cm
100 cg
100 cl
milli1,000 mm
1,000 mg
1,000 ml