Chapter 15
Measurement
Contemporary
Measurement Systems
U.S. Customary System
As we examine the table, we are unable
to identify a clear and logical pattern of
relations among the various.
Measurement Systems
There are two commonly used systems of
measurement today: the U.S customary
system and the metric system.
The growth the science and industry in
the eighteenth century, however,
required an efficient and convenient
way to measure length, weight, and
volume. The metric system of
measurement was created.
Almost all countries of the world have
adopted the metric system and made it
the official system of measurement.
The metric system has evolved over the
decades and has been modified into
what it is today.
The metric system, called le system
international d’unites, is known as SI.
SI provides eighth basic units listed in
the table below
In elementary and middle school
measurement, we commonly teach only
length, capacity, mass, temperature,
and time.
The basic unit of linear measurement
(length) in the metric system is the
meter
The other units of length in the metric
system are related to the meter by
powers of ten.
The names of the units of length based
on the meter are composed of two
parts, the base meter and a prefix that
indicates the relation of the unit meter
For example kilo is a prefix meaning
“one thousand”
So the term kilometer designates a unit
of length equal to one thousand meters
Conversion
Because the units of the metric system
are related in a simple and logical way
by powers of ten, it is easy to change
from one to another.
We need only to multiply or divide by
the appropriate power of ten.
You can convert between the various
different sizes by merely moving the
decimal point the correct number of
places.
The basic metric units are meters (for
length), grams (for mass or weight), and
liters (for volume).
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.
Two farmhouses that are 1300 meters
apart.
Suppose we want to express this
distance in kilometers. We know that
1000 meters is equal to 1 kilometer and
1
that each meter is equal to
of a
1000
kilometer. Therefore we can multiply
1
1300 by
or (0.01) and obtain 1.3,
1000
which is the distance between the 2
farmhouses in kilometers.
Conversion
The U.S. Customary system, however it
is much more cumbersome to change
units.
To remember the prefixes in order, you
can use the following sentence:
King Henry Doesn't [Usually] Drink
Chocolate Milk
kilo- hecto- deka- [unit] deci- centimilli-
Since each step is ten times or onetenth as much as the step on either
side, we have:
1 kilometer = 10 hectometers = 100
dekameters = 1000 meters
= 10 000 decimeters = 100
000 centimeters = 1 000 000
millimeters
Alternatively, we have:
Suppose, for example, that 2
farmhouses are 1.3 miles apart and that
we wish to express this distance in feet.
There are 5280 feet in one mile. So, we
must multiply 1.3 by 5280 to find the
distance in feet between the 2
farmhouses.
1 mile = 5280 feet
1.3 miles = 1.3 × 5280 =6864 feet
5280
× 1.3
1584.4 (.3 × 5280)
5280 (1 × 5280)
6868.0
To convert 1.3 miles into 6864 feet we
had to perform a three-step
mathematical operation.
Converting one metric measure to
another measure is a process that often
requires only a minimal amount of
mental mathematics.
Even though the conversion of
measurement within a given system of
measure is essential, conversion of
measurement from system to a different
system is not normally taught as part of
the elementary school mathematics.
Usually if a measure is given in metrics
units, the calculating will also be done in
metric measure.
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