Unit - how long a measurement is (usually feet, yard, inches, miles, etc.)
Perimeter - the distance around a figure (measured in units such as feet, yard, inches, miles, etc.)
Square Unit - a square with a side measurement of 1
Area - the number of square units inside of a figure (measured in square feet)
Volume - the amount of space that is taken up by a 3D figure (measured in cubic feet)