School librarians currently speak about school libraries as the largest classroom in the building. If so, how can these librarians describe what they teach? This article explains the user-centered instructional role of secondary school librarians in teaching information and technology literacy skills, as well as how they can authoritatively ensure that other educators, students, and the public know what they teach. To be certain, school librarians teach students how to use computer and information technology as tools to communicate and ethically conduct research. School librarians also have specialized expertise and skills, not only to facilitate, but to evaluate the accessed information. This evaluation is research-based and involves a knowledge building process that includes identification of five key terms: (1) data; (2) information; (3) knowledge; (4) wisdom; and (5) cognitive authority. This approach to information evaluation clarifies the complex digital world where information is self-organizing, self-correcting, and never finished. For future funding and survival, school librarians must make clear their critical role in improving instruction, boosting student achievement, and preparing today's children and youth for higher education and the work force. As this article points out, school librarians teach the use of computers and information technology as tools to improve communication, practice legal and ethical access, evaluate and use information, and to competently conduct research. School librarians, along with their school administrators and state department of education officials, should report that this specialized content is taught by the school librarian. (Contains 2 figures.)