Though the value of hands-on learning has long been recognized by educators, it is difficult to design laboratories in astronomy classes that present realistic astrophysical techniques to undergraduate students. Unlike most other sciences, astronomy is largely observational, not experimental, and making useful observations involves expensive equipment over time scales incovenient for pedagogy. In recent years, however, astronomy has gone almost completely digital, and the advent of large on-line databases and fast personal computers has made it possible to realistically simulate the experience of research astrophysics in the laboratory.

Since 1992, Project CLEA (Contemporary Laboratory Experiences in Astronomy) has been developing computer-based exercises aimed primarily at the introductory astronomy laboratory. These exercises simulate important techniques of astronomical research using digital data and Windows-based software. Each of the 9 exercises developed to date consists of software, technical guides for teachers, and student manuals for the exercises. CLEA software is used at many institutions in all the United States and over 60 countries world-wide, in a variety of settings from middle school to upperclass astronomy classes. The current design philosophy and goals of Project CLEA are discussed along with plans for future development. Project CLEA is supported by grants from Gettysburg College and the U.S. National Science Foundation.