would be settings or plots or climax or exposition or complication or even resolution
lots of details
You don't have to have a special setting for an unexpected ending - the setting is where and when the story takes place, so it could be anywhere and any time.
An author could use a familiar and ordinary setting to create a sense of complacency or predictability in the story before introducing a twist ending. By lulling the reader into a false sense of security with the setting, the unexpected ending can have a greater impact.
Not expected; coming without warning; sudden.
There are as many resolutions as there are authors - every story ends uniquely. You might have a "happy" ending, where everyone ends up succeeding (except for the villain, of course) or a "sad" ending where they fail. You might have a scary ending or a surprise twist or even a cliffhanger ending. It just depends on the author and their unique story.
It is unexpected yet it might happen or not.
you might find rising tides, and unexpected fog rolling in on summer days.
students would read minority authors
finding a sense of purpose in the story
"Endings" is rather a vague term. For our purposes, we shall treat the term "happy endings" as an ongoing event rather than a tertiary event. Any event can have a happy ending if there is a fortuitous outcome. This does not mean that the event turns out like the person expects. Most often there are unexpected outcomes, but in the main, an outcome that does not harm the person is a "happy ending". On the other hand, what often is seen as a "happy ending" is not. The person involved might get the wished for outcome, but it might not be the "ending" that was best for the person. Serendipity often plays a part in the idea of "happy ending." And unexpected outcome of an event can often look like a sheer disaster for the person. But in the end, a person becomes stronger, wiser, or more experienced with each event. Therefore it is this writer's experience that, even though it doesn't initially look like it, all people get their "happy ending".
A general setting would be something like USA in the 50's, whereas a specific setting might be Los Angeles, California in 1956
To anger or outrage the audience in order to force them to take action