What: A scene entering on one value (trust) and exiting on its opposite (doubt).
Why: A scene that changes nothing is dead; the turn pushes the story and keeps the viewer.
How: Identify the value at the scene's start and let an event or reveal invert it before its end.
Common mistake: Scenes that only convey information without changing the character's state.
Exercise: Take a static scene of yours and add a small reveal that turns its value in the last line.