**The Metric System**

**There are four basic metric measurement units:**

• Length = **meter** (m)

• Volume = **liter** (l)

• Mass (weight) = **gram** (g)

• Temperature = ° **Celsius** (° C)

All four metric system basic units can be converted into larger or smaller units simply by adding a prefix in front of the basic unit:

** Unit prefixes:**

**kilo (k)**= Makes the basic unit 1000 times larger (10^{3})**deci (d)**= Makes the basic unit 10 time smaller (10^{-1}or 1/10)**centi (c)**= Makes the basic unit 100 times smaller (10^{-2}or 1/100)**milli (m)**= Makes the basic unit 1000 times smaller (10^{-3}or 1/1000)**micro (µ)**= Makes the basic unit a million times smaller (10^{-6}or 1/1,000,000)

*For example, a person might weigh 63,000 grams. That same person also weighs 63 kilograms (kg) since each kilogram is equal to 1000 grams.*

*These larger and smaller units are called “derived” units*

**A) Length**

The basic unit of length in the metric system is the meter (m). Common derived units are the centimeter (cm) (10^{-2} or 1/100 of a meter) and the millimeter (mm) (10^{-3} or 1/1000 of a meter). For measuring large distances, the kilometer (10^{3} or 1000 meters) is often used.

**B) Volume**

The basic unit of volume in the metric system is the liter (l). The most common derived unit is the milliliter (ml) (10^{-3} or 1/1000 of a liter). The volume of a milliliter is equal to the volume of a cube 1 centimeter per side.

(The ml is often called the cubic centimeter (cc) in the medical field).

Another derived unit is the micrometer (µl) (10^{-6} or 1/1,000,000 of a liter).

**C) Mass (weight)**

The basic unit of mass in the metric system is the gram (g). The most common derived unit is the milligram (mg) (10^{-3} or 1/1000 of a gram). For measuring large masses, the kilogram (10^{3} or 1000 grams) is often used.

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**D) Temperature**

The basic unit of temperature in the metric system is the degree Celsius.

(° C ). There are no commonly derived units.

To get a feel for degrees Celsius, consider the following temperatures:

• Ice water and the freezing point of water are 0 ° C

• Room temperature and tap water are 20 – 25 ° C

• Normal body temperature is 37 ° C

• Water gets too painful to touch between 50 – 60 ° C

• Water boils at 100 ° C