I'm taking an introductory HTML class and am struggling with some of the crazy questions we are assigned. I mean I know I don't know much about web design but these questions just don't seem to make sense. For example here is one of them;

Q: "What is a site map? Give an explanation and examples. Find at least 3 sites that explain how to use site maps. What are the pros and cons for site maps. Show picture examples of site maps."

Now, I know basically that a site map is an index page for a website that simply lists all the links, or if spelled Sitemap it can mean an XML page that you can submit to Google, but "Find at least 3 sites that explain how to use site maps" throws me. I can't find any such sites and have no idea why there would be any such sites. Also "What are the pros and cons for site maps" makes no sense to me. I have no idea what this instructor is fishing for. Do these questions make sense? Thanks.

Just google site maps.

Or , Site maps how to.

all they do is as you said list all links on your website.
Most importantly the main reason for a sitemap is so sites like google can find pages it may not otherwise find.

Lets say you have a page that NO other page links to, or via a path that it cant follow.

How is google going to find it?
A sitemap shows google ( and others ) where to look.

You could think of a sitemap as an index, just like you'd find at the end of a book. As lynxus said, all a sitemap is, is literally a list of every page/URL on the site. On bigger sites there may be 2,3 or more sitemap files.

The spelling, site map or sitemap, is irrelevant