Our library uses the Library of Congress (LC) call number system to classify books and other materials according to subject area.  For example, class L designates works on education generally, while subclass LA denotes works on the history of education, subclass LB is associated with works on the theory and practice of education, subclass LC includes works on "special aspects" of education (forms of education, social aspects of education, moral and religious education, etc.), and so on.

The general outline of Library of Congress classifications can be found at http://www.loc.gov/aba/cataloging/classification/lcco/, and by clicking on any of the general categories, it is possible to find a very detailed schedule of specific call number ranges within the secondary level of subclasses under the broad overall class.  For example, here is the full outline for call number ranges within the L (Education) classification category

The Library of Congress classification system is decimal-based, and understanding the correct shelving order by call number can be a challenge.  You can find useful explanations of LC classification features and shelving rules at such websites as the University System of Georgia and the American Museum of Natural History.