Nature of Science
Metric SystemInternational
System of Units
(SI)
Learning Targets:

Use appropriate tools and equipment for
measuring

Use the metric system for measuring

Use the “ladder method” and dimensional
analysis to convert values between
metric and English units
The Metric System

Standardized system of measurement
used by all scientists worldwide.

Based on units of 10

Similar to our monetary system:
10 cents = dime
100 cents = dollar
10 dimes = dollar
Why use the SI System?
Scientists use the SI
System worldwide
because:

Measurements are easily understood by all scientists

Measurements are easier to convert than the English
system
The Metric System is used for everyday life in
most countries except the United States, Liberia
and Myanmar
In the English system you have to
remember so many units numbers . . .





12 inches in a foot
3 feet in a yard
5,280 feet in a mile
16 ounces in a pound
4 quarts to a gallon
In the SI System you only have to
remember one number - 10 and a few
basic units
Basic Types of Measurement
Length: measures distance between objects
Volume: measures the amount of space
something takes up
Mass:
measures the amount of matter
in an object
Temperature: measures molecular movement
in an object
Measurement System
MEASUREMENT
BASIC UNIT
ABBREVIATION
LENGTH
Meter
m
VOLUME
Liter
L
Celsius
°C
MASS
Gram
g
TIME
Second
s, sec
TEMPERATURE
All Measurement systems have standards.
Standards are exact quantities that everyone
agrees to use as a basis of comparison.
1 Gram
1 Liter
1 Meter
Weight
vs.
Measure of the force of
gravity on an object
Mass
Measure of amount
of matter in an object
NOT affected by gravity
Weight vs. Mass
Weight and Mass are related, but NOT the same.
 Weight can change depending on location
 Mass is constant regardless of location
 The greater the mass, the larger the pull of gravity.
The larger the pull of gravity, the greater the weight
Mass Vs. Weight Poster Activity
Metric Base Units
The Base Unit is the determined by
the type of measurement being
made. (mass, volume, or length)
Metric units
Meter
Measurement of distance
or length
Liter
Gram
Measurement of volume
Measurement of mass
Metric System Prefixes
Kilo
1000
Hecto
Deca
100
10
Base Unit
g, m , L
1
Deci
.1
1/10
.01
1/100
.001
1/1000
Centi
Milli
The same prefixes are used
regardless of the
measurement type being
made length, mass, or volume.





Pass out a handout and a ruler.
Write your name in the upper right corner.
Locate the column of prefixes.
Draw a line above kilo- all the way across
the page – edge to edge.
Draw another line below milli- all the way
across the paper – edge to edge.
Directions
Does your paper look like this?
You must
memorize
the prefixes
between
the lines
drawn.







KiloHectoDeka(unit of measure, or meter–liter-gram)
DeciCentiMilli-
Let’s say them together….
Practice
Abbrev.
mm
cg
kL
cm
mL
mg
km
kg
Word
millimeter
Meaning
one thousandth meter
Abbrev.
mm
cg
kL
cm
mL
mg
km
kg
Word
Meaning
millimeter .001 meter (thousandth)
centigram .01 gram (hundredth)
kiloliter
1000 liters
centimeter .01 meter (hundredth)
milliliter
.001 meter (thousandth)
milligram
.001 gram (thousandth)
kilometer
1000 meters
kilogram
1000 grams
“Ladder Method”
• Used for metric to metric conversions
• Conversions are done by moving the decimal
point.
• Larger to smaller unit:
Move decimal point to the right
• Smaller to larger unit:
Move decimal point to the left
Let’s practice…
Take out a piece of scratch paper and write this
problem down:
• 3.4m = _________ cm
• Put your pencil on the decimal (.)
• Put your finger on (units) where m would be.
• Move your finger right 2 times to cm.
• Move the decimal right 2 times.
Did you get this answer…
•
•
•
•
•
3.4m = 340 cm
Great!
Let’s try another.
500mg = _______ g
Use the same procedure. Put your pencil on
the decimal and your finger on the
corresponding space and move.
Ready…Set…Move….
• 500mg = _____g
• Put your pencil where the decimal should be and
your finger on the mg box.
• Move your finger 3 times left then move the decimal
3 times left.
• Did you get…
• 500mg = .5g
• Good job!
One more time…
•
•
•
•
•
•
.2kL = ______ L
Pencil on the decimal and finger on the chart.
Count 3 right then move the decimal 3 right.
Did you get…
.2kL = 200L
Yea!
That was easy…
• Practice just a few then check your answers
with a partner.
•
•
•
•
3.5 cm = _____mm
500 mg = _____g
2L = _____mL
.25km = _____m
Check your answers
Did you get…
• 3.5 cm = 35 mm
• 500mg = .5g
• 2L = 2000mL
• .25km = 250m
• Now all you have to do is practice, practice,
practice….
Metric Conversion Challenge
** Pass Out Handout **
Things to Remember




All measurements need a
number and a unit!
Basic units of Measurement
(meter, liter, gram)
Metric prefixes and values
How to convert units
Metric Measurement: Length
Length is the distance between two points.
 Does not matter if it is width, height, depth, etc.
All are length measurements.
 The basic unit of length in the SI System is the
meter.
 The meter is about the length of the English yard
(3 feet).
 Area is a variation of a length measurement.

Area is length x width.

Expressed in units2 (m2, cm2, mm2 etc.)
Metric Measurement: Mass
Mass is a measurement of the amount of matter in
an object.
 Basic unit of mass is the gram. There are
454 grams in one pound.
 Weight and mass are related, but NOT the
same.

Weight is the pull of gravity on an object

The greater the mass, the larger the pull of
gravity.
Metric Measurement: Volume
Volume is a measurement of the amount of space
something takes up.
 The basic unit used for volume is the liter. This
unit is used for the volumes of liquids.
 Volumes of solids are figured using this formula:
(L)ength x (W)idth x (H)eight
cm x cm x cm = cm3
 Objects without a definite length, width or
height (a rock for example), can use water
displacement to determine volume.
NOTE: 1 ml = 1 cm3
Metric Measurement: Temperature
Temperature is a measure of the kinetic
energy of the atoms in an object.
 Temperature is measured with a thermometer
and measured in Celsius or Kelvin.
 Celsius ranges from 0 (freezing) to 100 (boiling).
 The Kelvin scale begins at absolute zero, or 0 K.
At 0 Kelvin no more heat can be removed from
an object.
 To convert to Kelvin you add 273 degrees to
the Celsius reading.
 Freezing in Kelvin is 273 K, boiling is 373 K.