Listed below are several links we like for information on the measurement of land.
The basics we use almost daily are:
1 acre is: 43,560 square feet, 4,840 square yards, 208 feet 8.5 inches square.
A football field is 1.32 acres in size.
There are 640 acres in a section of land, 320 in a half section, 160 in a quarter
section, etc.
A section of land is 1 square mile. 36 square miles make a Township.
If you want to get more technical and refer to rods, links, chains and other units, click on one of the links below. They go into great detail about these and other surveying matters.
http://www.unc.edu/~rowlett/units/A Dictionary of Units of Measurement. Look up the meaning of almost any unit of measurement you are likely to ever hear of. Educational and useful information.
http://extension.oregonstate.edu/catalog/pdf/pnw/pnw581.pdf
An interesting and informative booklet on the science and math of land measurement and surveying.