[citation needed] Riddell taught in the theater department at the University of California, San Diego from 1978 to 1987.
and James H. Semans Professor of the Practice of Theater Studies,[1] teaching classes such as "Arts and Contemporary Society", "Lighting Design for the Theater", and "Arts and Stage in the 20th Century".
He also worked on the scene design for 'Krapp's Last Tape for Akademie der Künste, Akhnaten, and The Yellow Sound.
[citation needed] In 1986 he received a Knox College Alumni Achievement Award.
[4] Riddell has published many articles in different magazines and newspapers, such as American Theater, The New York Times, TheaterWeek, The Drama Review, The Chronicle of Higher Education, Contemporary Designers, and Theater Crafts.