If you find yourself working in a public library chances are good that it will use the Dewey Decimal System. Melvil Dewey is certainly represented on the web and in the blogosphere.
The following places of interest are a quick look at some of the resources available to help you learn and understand about the classification system. If you are taking Library 105B you are hip deep in the Dewey so hopefully I can dig out additional resources for the class.
The official Dewey site Online Learning Computer Center (OCLC) contain a gateway to the world of classification. You can download a copy of Introduction of Dewey Decimal Classification. In 37 pages it will give you the history, the classification schedules and the beginning steps on how to determine a subject, Notation, field of study and working with schedules and tables.
You will also want to check out the glossary of Dewey terms. Students in certain LT classes have access to Web Dewey but if you would like to get a head start on how to use the Web Dewey feature you can view a Power Point tutorial.
Outside of OCLC another place you want to visit is the Dewey Blog, edited by Johnathan Furner and the DDC team. If you can think it there is (or will be) a Dewey number for it. The blog represents life as viewed by the DDC. One of the entry that had me blinking was the classification of the toys and lead problems that have been in the news.
They go through the process of how this topic has been classified and what they do when there is not an exact match in the classification system. It is also a good opportunity to observe how a DDC "built" numbers are constructed.
Not every public library has Dewey, in fact there are a few that stopped using Dewey numbers such as the one in Arizona. They will arrange books by topic instead.
This has generated a lot of posts. Daniel DeStefano isn't crazy about the idea. A Library By Any Other name blog suggest that one of the problems with patrons finding books is that there isn't the right kind of signs or visual cues that would make it clear that where to find the history book.
Not all folks hate the idea of pitching Dewey - some folks like Shelly from A View From Here mention that maybe there could be a merger between the bookstore model and the traditional library classification systems.