MEASUREMENT
FOUNDATIONS OF SCIENCE
ESSENTIAL QUESTIONS
WHAT IS A SCIENTIFIC MEASUREMENT?
 WHAT IS THE DIFFERENCE BETWEEN ACCURACY AND
PRECISION?
 WHAT IS A SYSTEMATIC METHOD OF CONVERTING
FROM ONE MEASUREMENT UNIT TO ANOTHER?

MEASUREMENT

A DETERMINATION OF THE
AMOUNT OF SOMETHING

CONTAINS A NUMBER VALUE
AND A UNIT

THE NUMBER IS USELESS
WITHOUT A UNIT ATTACHED
TWO COMMON MEASUREMENT
SYSTEMS

ENGLISH SYSTEM
INTERNATIONAL SYSTEM
USED BY PEOPLE IN THE UNITED
STATES – INVOLVES UNITS SUCH
AS MILES, FEET, CUPS,
TEASPOONS, POUNDS, PINTS,
QUARTS, GALLONS AND INCHES –
lots of different relationships

CALLED THE SYSTEM
INTERNATIONAL (SI UNITS) AS
COINED BY THE FRENCH AND
ADOPTED BY THE UNITED
STATES IN 1960 – INVOLVES
UNITS WHICH ARE ALL BASE 10
OR IN THE DECIMAL SYSTEM
COMPARE THE TWO SYSTEMS
ENGLISH SYSTEM – YARD STICK


1 YARD = 36 INCHES = 3 FEET
SMALLEST DIVISION IS 1/32ND OF
AN INCH IN MOST CASES – A
FRACTION OF AN INCH – TOUGH
TO ESTIMATE THE MEASUREMENT
SOMETIMES – based on fractions –
¼, 1/8, 1/16, etc.
INTERNATIONAL SYSTEM – METER STICK


1 METER = 100 CENTIMETERS = 1000
MILLIMETERS
SMALLEST DIVISION IS A 1/10TH OF A
CENTIMETER OR ONE MILLIMETER –
NOT A FRACTION, BUT 0.1 – EASIER
TO ESTIMATE THE MEASUREMENT –
based on decimals!!
COMMON SI UNITS
ACCURACY OF A MEASUREMENT



HOW CORRECT THE
MEASUREMENT IS
IS IT CLOSE TO THE TARGET
VALUE YOU ARE AIMING
FOR?
DETERMINED BY
CALCULATING A PERCENT
ERROR FOR THE
MEASUREMENT
CALCULATE THE PERCENT ERROR
 If
the density of an object
is found to be 7.62 g/ml
in the laboratory, what is
the percent error if the
reference density is 7.48
g/ml?
PRECISION OF A MEASUREMENT



HOW CLOSE THE
REPEATED
MEASUREMENTS ARE TO
EACH OTHER
HOW CONSISTENT THE
MEASUREMENTS ARE
FOR A MEASUREMENT,
PRECISION IS REFLECTED
IN HOW MANY SIGNIFICANT
DIGITS ARE IN THE VALUE
PRECISION DEPENDS ON MEASURING
INSTRUMENT
WHICH INSTRUMENT HAS BETTER PRECISION IN
MEASURING THE VOLUME OF WATER?
MAKE THIS MEASUREMENT
In making a measurement,
you are only allowed to
estimate one digit.
 All other digits are known
for certain!!!
 The digits known for
certain and the one
estimated digit are known
as SIGNIFICANT DIGITS!!!!

ACTIVITY
You will be working with a partner to complete a packet in
which you thoughtfully make several scientific measurements,
reporting all significant digits.
ACCURACY VS PRECISION
TIME




TWO WAYS TO THINK ABOUT TIME
 WHAT TIME IS IT?
 HOW MUCH TIME? (TIME
INTERVAL)
TIME COMES IN MIXED UNITS
YOU MAY NEED TO CONVERT
HOURS AND MINUTES INTO
SECONDS
HOW MANY SECONDS DOES THE
TIME INTERVAL REPRESENT?
DISTANCE




THE AMOUNT OF SPACE
BETWEEN TWO POINTS
MEASURED IN UNITS OF
LENGTH
THE METER IS THE BASIC SI
UNIT
PREFIXES ARE ADDED TO
REPRESENT EITHER
MULTIPLES OF THE METER OR
PARTS OF THE METER
1 MEGAMETER = 1,000,000
METERS
1 KILOMETER = 1000 METERS
100 CENTIMETERS = 1 METER
1000 MILLIMETERS = 1 METER
1,000,000 MICROMETERS = 1
METER
MASS


THE AMOUNT OF MATTER IN
A SAMPLE
MEASURED IN THE SI UNIT
OF KILOGRAM
1 MEGAGRAM = 1,000,000 GRAMS
1 KILOGRAM = 1000 GRAMS
100 CENTIGRAMS = 1 GRAM
1000 MILLIGRAMS = 1 GRAM
1,000,000 MICROGRAMS = 1 GRAM
VOLUME


THE AMOUNT OF SPACE
TAKEN UP BY A SAMPLE
MEASURED IN SI UNITS OF
LITERS
1 MEGALITER = 1,000,000
LITERS
1 KILOLITER = 1000 LITERS
100 CENTILITERS = 1 LITER
1000 MILLILITERS = 1 LITER
1,000,000 MICROLITERS = 1
LITER
COMPUTER LANGUAGE
METRIC PREFIXES



WHAT IS CONVENIENT IS THAT THE PREFIX
INDICATES MAGNITUDE WHICH DOES NOT
DEPEND UPON WHAT IS BEING MEASURED
FOR EXAMPLE, GIGA MEANS A BILLION OR
1,000,000,000 OR 109 WHETHER IT IS A
GIGABYTE, GIGAGRAM, GIGASECOND,
GIGALITER, OR GIGAMETER.
THE MAGNITUDE IS THE SAME, THE BASE
UNIT REFLECTS WHETHER IT IS A MASS,
VOLUME, TIME, COMPUTER STORAGE, OR
DISTANCE MEASUREMENT.