This unit (which consists of a single lesson) describes the structural and operationally unique features of aerated lagoons. In addition, special troubleshooting and maintenance problems are discussed. The instructor's guide for the unit includes: (1) an overview of the lesson; (2) lesson plan; (3) lecture outline (keyed to a set of slides used with the unit); (4) student worksheet (with answers); and (5) two copies of a final quiz (with and without answers). This unit is heavily dependent upon information presented in the facultative lagoon unit and it is recommended that both units be presented as a set. If it is necessary to present only aerated lagoons, material from the facultative lagoon unit should be referenced and students encouraged to read it ahead of time. (JN)