Libraries use classification systems such as the DDC or LCC to assist with keeping their materials organized on their shelves, but that’s not the only thing that they might use. They might have separate sections to group similar items together. For example, they might have a DVD collection. These may or may not use DDC or LCC, but they will be organized separately from the books. Likewise, there may be a Reserves section, which you may not be able to browse yourself, but you might be able to search for through the library search tool.
What other collections does your library have that might be separated within the library? How will you be able to search for items in those collections? What do you need to know in order to find those items in the library?