Scene
A scene is a unit of action: an obstacle, the plan the protagonist has to overcome the obstacle, the events that complicate the protgonists efforts to overcome the obstacle, her success or failure, leading to further complication.
A scene can be thought of as its own story in minature: complete with rising tension, mini-climax and a resolution which is not final, but leads to more complications as the protagonist continues to pursue the primary objective of the narrative.