Length  Metric System
The metric system was developed during the French Revolution. Thomas Jefferson promoted it in the United States, but the system was not legalized until 1866. In 1902 Congress voted to require the United States Government to use the only the Metric System. The vote was defeated by one vote.
The metric system is much easier to use than the Customary System, because you do not have to remember different conversions such as 12 inches equal a foot, 3 feet equal a yard, and so on. All you have to remember is a list of prefixes that represent powers of 10.
Prefix 
milli 
centi 
deci 
meter 
deka 
hecto 
kilo 
Abbreviation 
m 
c 
d 
m 
d k 
h 
k 
Example 
milliliter 
centimeter 
decimeter 
meter 
dekameter 
hectometer 
kilometer 
Multiplier 
0.001 
0.01 
0.1 
1 
10  100  1000 
The hardest thing is to get the feel of units the Metric System uses. How big is a centimeter? a meter? and so on? The chart below will help you.
millimeter  mm  centimeter cm  decimeter  dm  meter  m  kilometer  km 
1 centimeter = 10 millimeters 
1 decimeter = 10 centimeters 
1 meter = 10 decimeters 
1 kilometers = 1000 meters 

The edge of a dime is approximately 1 millimeter. 
A paperclip is approximately 1 centimeter wide. 
A crayon is approximately 1 decimeter long. 
The distance from the floor to the door knob is approximately 1 meter. 
The length of 6 city blocks is approximately 1 kilometer long. 
Now that you know the basics you can go to practice activity for metric length.
More Practice from Other Sites
FunBrain Site
AAA Math