Created by staff members at the University of Washington's Astronomy Department, this online clearinghouse consists of applications, lectures, and in-class activities is designed to be used in a range of introductory astronomy courses. The materials here are divided into eight areas, including "Observing the Sky", "Solar System", "Stars", and "Milky Way Galaxy". Visitors can download each file for their own use, and while there is no formal search engine on the site, it's easy enough to just scroll down to see each item. The "The Sun" and "Stars" areas are both true gems, and they each contain at least five separate items that can be used in classrooms to illustrate ideas and concepts that include distance measures and identifying lines in the solar spectrum.