A field test of PLATO IV computer-assisted instructional lessons is discussed. Biology classes at three city colleges of Chicago used PLATO IV as part of the Community College Biology Project. During the 1974-75 academic year, usage involved 49 classes, 1506 students, and over 8700 hours on the system. Approximately 53 PLATO biology lessons were available for use. Practical knowledge obtained from the major areas of teacher-user orientation, lesson design strategies, documentation of the implementation process, and lesson validation are described. Sample lessons are included. (MH)