VERY IMPORTANT!!!!

All measurements must have a number and a unit!!!

Here in America we use…..

the ENGLISH SYSTEM

But EVERYONE else uses….The Systeme International d’Unites

ORInternational System of Units (SI Units)

Seven Base SI UnitsWhat is measured…

1. Mass2. Length3. Time4. Quantity5. Temperature6. Electric Current

7. Luminous Intensity

Unit and symbol….

1. Kilogram, kg2. Meter, m3. Second, s4. Mole, mol5. Kelvin, K6. Amphere, A7. Candela, cd

Derived SI UnitsDerived SI Units - combination of SI base units

Example: Area = Length x Width Area = 4.0 m x 2.0 m

Area = 8.0 m2

Remember to multiply both the number and the unit!!!!

Non-SI UnitsNon-SI Units - commonly used

units that are not derived from the SI base units

The most common example is the LITER used to measure volume.

Also common is temperature measured in oC (Celcius).

PrefixesPrefixes - make a SI Unit smaller or larger by a factor of 10.

Prefixes are attached to the front of the base unit.

Ex: millimeter or kilometer

Kilo Hecto Deca BASE UNIT

Deci Centi Milli

k h da d c m

1000 100 10 1/10 1/100 1/1000

BASE UNIT

gram (g)Liter (L)

Meter (m)