This supplement updates the original catalog of available PLATO system instructional materials which was published in April 1980. The lessons described have been used in actual instructional situations, or have had adequate testing to guarantee that the files are in working order. Printed directly from the CERL online catalog, "unicat," the information provided for each citation includes the subject, a subheading, a title with its PLATO code, year of first copyright and publication date, author, location of the author at the time the lesson was produced, an abstract, auxiliary equipment required, lesson completion time, and intended audience. Library of Congress subject headings have been used to catalog the lessons whenever possible, and extensive cross references are provided. The materials listed range in level of difficulty from the primary level through higher education, and embrace a wide variety of disciplines; e.g., reading; basic mathematics; languages,including English composition and English as a second language; business and accounting; botany, chemistry, and physics; algebra; statistics; engineering education; teacher training; and medical education, including simulations for physicians, nursing, and pharmacology courses. (LLS)