It can also be used for TODO lists, etc, which are all things a teenager can make ample use of.
For example, on mine, I have sections for Courses, Places (the pages I visit every day or so), Lisp (stuff dealing with Common Lisp specifically, that I access often), Text-to-Voice (something I'm researching), and a whole bunch of things that I need to occasionally reference that can be self-contained in html-style tables.
It's a whole lot better than losing things among a huge pile of mainly invisible bookmarks (although I use them, too), and it is easy to prune as time and interests go on.