Final answer:
Viola Spolin used improv in her lessons during the 1920-30s and her son, Paul Sills, further developed improv teaching in the 1950s.
Step-by-step explanation:
The famous teacher who used improv within lessons during the 1920-30s was Viola Spolin. She is recognized as an important innovator in the field of improvisational theater. Her son, Paul Sills, followed in her footsteps and further developed the teaching of improv throughout the 1950s.
While Commedia dell'Arte was an influential actor-driven theatre in Italy, developing in the 16th century, it was not the answer to the specific question asked. The University of Calgary represents an institution and not an individual teacher, and The Second City is an improvisational comedy enterprise founded later in 1959.
In the field of acting and improvisation, Viola Spolin's work laid essential groundwork, and Paul Sills took the family legacy forward in the United States by establishing institutions like The Second City in Chicago that have perpetuated the legacy and learning of improvisational theater.