Most public libraries and K-12 libraries use the Dewey Decimal Classification (DDC) system to organize books by subject area. This will look different than the Library of Congress (LC) classification system that you may be used to using at college and university libraries like ours. To learn more about the Dewey Decimal Classification System you can find some helpful resources at: http://www.oclc.org/dewey/resources/public.en.html
Non-Fiction books in the public and K-12 libraries that use the DDC will generally be found in the same Dewey Decimal areas in both juvenile and adult areas.
Fiction books will be shelved by the first three letters of the authors last name, but can be found by using the keyword search with the subject term of your topic.