Improvisation has a teaching tradition because spontaneity still has craft. An unscripted scene depends on readable actions, relationships and responses. Teachers have approached that problem through games, through theatre structures and through the working habits of ensembles. Their approaches are related, but their names are not interchangeable labels for a single method.
This page follows the people and roles described in the cited references. It concentrates on teaching and theatrical form, rather than private biography or a list of performers they taught. The history of improvised theatre follows the wider movement between games, companies and performance forms. Here the emphasis is on the ideas that can still be recognised in a rehearsal room.
Viola Spolin and Neva Boyd: a focus for play
Wikipedia describes Viola Spolin as an educator and acting coach whose Theater Games gave performers a specific focus or theatre problem. It identifies Neva Boyd as her teacher and describes the influence of Boyd's work with recreational games. Spolin's book Improvisation for the Theater brought her games, philosophy and coaching methods into a written reference.
The focus matters because it gives players something definite to do within an open scene. A game can draw attention to the imagined environment or the relationship without deciding what the scene will contain. The task and the response coexist. This way of describing theatre separates the demand for a clear action from the demand for a clever idea.
Boyd's place in this account is as Spolin's teacher. The relationship helps explain how a practice of shared games could become a theatre teaching approach. It does not make every later game identical or every classroom a performance space. Spolin's work gives improvisation a language of attention that can be carried into different theatrical settings.
Paul Sills: games within directed theatre
Wikipedia's article on Paul Sills identifies him as a director and improvisation teacher, and as the original director of The Second City. It describes his use of Spolin's techniques and revues developed through improvisation under his direction. The relationship between directing and improvisation is central to that account.
A director can give an ensemble a frame while the players discover material through action. An improvised scene and a finished revue are different results, but improvisation can be part of the process leading to either. This makes the teaching room more than a preparation for a performance that will remain unscripted. It can also be a place where dramatic material becomes visible for further theatre work.
Sills's role places games among the ordinary decisions of theatre: how performers share a space, how a relationship becomes clear and how an audience follows action. The value of a game as a theatre tool is understood through the work it frames, rather than through an abstract promise about creativity.
David Shepherd: an ensemble working from outlines
Wikipedia's account of the Compass Players identifies David Shepherd as the founder and describes his idea of plays improvised from outlines or scenarios. It records Shepherd turning to Paul Sills to direct the venture, with Sills using Spolin's Theater Games in rehearsal. The outline supplied a frame; the performers supplied the action within it.
This example makes an important distinction in theatre language. Unscripted does not have to mean that nothing has been decided before the performance. An outline can establish a broad situation while leaving dialogue, behaviour and exchanges to the ensemble. Improvisation concerns the choices being made in the moment, including choices made within an existing structure.
The ensemble therefore has a shared task without a finished scene to reproduce. An outline and a game frame the work differently, yet both can give spontaneous action a context. The account of improv teaching explains how classroom language distinguishes the task, the scene and the structure around it.
Del Close: connections across scenes
Wikipedia's article on Del Close identifies him as an actor, author and teacher, as a co-founder of ImprovOlympic, and as a figure in the development of the Harold. His place in this account concerns teaching and longform structure. The form provides a way for characters, themes and choices to gain meaning through later returns.
A connection across scenes asks an ensemble to remember more than a plot. It may involve a relationship, a pattern of behaviour or a contrast that becomes clear after another scene has appeared. Longform craft includes that continuing attention. A scene can stand on its own while also carrying material that the group will recognise elsewhere.
The Harold is useful to discuss as a structure rather than as a guarantee of a particular comic result. Its relationships are created by the ensemble's present choices. Naming the form makes the frame legible; the performers still have to make each return belong to the developing work.
Keith Johnstone: a teaching system and competitive theatre
Wikipedia describes Keith Johnstone as an educator and theatre director associated with an improvisation teaching system, Theatresports and his book Impro: Improvisation and the Theatre. The reference describes his work with performers through games and other theatre tasks. Theatresports places improvised scenes within a competitive performance frame.
Competition changes the context around a scene. An audience can follow a result or a contest as well as the characters' actions. The theatre inside that frame still depends on offers and responses. Describing the competitive structure does not replace an account of the craft that makes its scenes readable.
Charna Halpern: a home for continuing longform work
Wikipedia identifies Charna Halpern as a co-founder of iO with Del Close and describes their adaptation of the longform style called the Harold. Her role makes the connection between an artistic approach and an institution visible. A theatre and teaching centre can provide an ongoing context for ensembles and a shared form.
These accounts meet in practical craft without collapsing into a single doctrine. Games give attention a frame; outlines and forms give scenes a larger shape; teaching and rehearsal give those choices names. The improviser's toolkit follows agreement, listening and character at the scale of a scene, where those ideas become visible through the next response.