Describe what changes from the beginning of the scene to the end in one plain sentence. Avoid emotion, interpretation, and performance language at first.
For example: he does not have the keys, then he finds them. She believes the relationship is secure, then her partner ends it. They do not know who committed the crime, then new information gives them a suspect.
The event is the scene’s movement from point A to point B. It helps you understand why this moment belongs in the story. If your summary requires a paragraph, strip away the dialogue and ask what is newly known, gained, lost, decided, or changed. Once the event is clear, you can ask what your character wants inside it and how the change affects them.