Instructional materials for teaching junior high school students about the Dewey decimal classification system for books and about library catalog cards are presented in this unit from the Greenfield Express Management System (GEMS) program, a California Demonstration Program in Reading. A project overview form from the California Centers for Educational Improvement (CCEI) describes the GEMS program and lists other units included in the program. This unit includes: (1) instructions for the teacher; (2) a list of Kern County (California) filmstrips and unipacs on library science which can be used as follow-up activities; (3) an explanation of the Dewey decimal system; (4) an activity involving sorting books into Dewey classifications; (5) an explanation of author, title, and subject catalog cards; (6) an activity using these cards; and (7) a word-matching test involving terms used in this unit. (DC)