This instructor's guide contains the materials needed to teach a seven-lesson unit on activated sludge. These materials include an overview of the unit, lesson plans, lecture outlines (keyed to slides designed for use with the lessons), student worksheets for each of the seven lessons (with answers), and two copies of a final quiz (with and without answers). Topic areas addressed in the lessons include: (1) review of activated sludge concepts and components (including aeration tanks, aeration systems, clarifiers, and sludge pumping systems); (2) activated sludge variations and modes; (3) biological nature of activated sludge; (4) sludge quality and respirometry for process control; (5) return sludge control; (6) waste sludge control; and (7) trend charts, testing, and data management. (JN)