Imperial Units (Sometimes called English Unitsor Customary Units)

The basic units for length or distance measurements in the Imperial system are the inch, foot, yard, and mile. Other units of length also include the rod, furlong, and chain.

The units in bold below should be memorized. Other units are less common and are only in the honors assessments.

1 foot         =     12 inches
1 yard        =    3 feet         =    36 inches
1 rod        =    5.5 yards
1 chain     =     4 rods        =    66 feet
1 furlong    =    10 chain    =    40 rods
1 mile        =    1,760 yards    =    5.280 feet

Metric Units

The basic unit of length in the SI (Internation System of Units) system is the meter. The meter was originally intended to be one ten-millionth of the distance from the Equator to the North Pole at sea level. The meter has since been redefined as the distance traveled by light in a vacuum in 1/299,792,458 seconds. Subdivisions of the meter are the millimeter, centimeter, and decimeter. Multiples of the meter include the decameter, hectometer, and kilometer.

The units in bold below should be memorized. Other units are less common and are only in the honors assessments.

1 meter    =    1,000 millimeters
1 meter    =    100 centimeters
1 meter    =    10 decimeters
1 decameter    =    10 meters
1 hectometer    =    100 meters
1 kilometer    =    1,000 meters