What does a school librarian do?
Today's school librarian works with both students and teachers to facilitate access to information in a wide variety of formats, instruct students and teachers how to acquire, evaluate and use information and the technology needed in this process, and introduces children and young adults to literature and other resources to broaden their horizons. As a collaborator, change agent, and leader, the school librarian develops, promotes and implements a program that will help prepare students to be effective users of ideas and information, a lifelong skill.
-From AASL Website
http://www.ala.org/aasl/about/ed/recruit/learn