I did Arthur Miller's play "The Crucible" in Year 10. I had the worst teacher, who gave us non-stop essays on it. Of course in Year 10, we didn't view it on changing perspective and I had little knowledge of knowing how to write an essay. Despite the fact that I got mainly A grades for my essays, I suspect the quantity of the essays I wrote kind of put off the teacher and she could not be bothered reading it (there were no comments on it) and gave an A for all that effort regardless of content!! lol!!
Anyway, "The Crucible" is based on Arthur's 20th century experience with McCarthyism. It's about how innocent people are being executed for witchcraft, because of the hysteria of strange happenings in Salem. Specifically Abigail accuses many people for witchcraft and they are eventually hanged, for the sake of Abigail's jealousy of Elizabeth (Proctor's wife). Abigail uses her convincing youthful innocence to make it seem that she is the victim of witchcraft when in fact she is trying to steal Proctor from Elizabeth, because Proctor had once committed adultery to her. As a result, Proctor gets executed against Abigail's will, because he has refused to sign a confession of adultery to save his name.
The main play or climax is not too bad to understand, its just the details and profiles that you read and the beginning of the play that makes it kind of confusing. I have also watched the film version, which I reckon shows everything more clearly, but some main scenes in the play are omitted in the film.
From the top of my head, I'd say the main changing perspective in the play would be the attitudes of society. The people's perpsective of who is innocent and who is guilty changes constantly. e.g. Proctor had a good reputation in Salem, but as he is hanged, the people change their perspective on witchcraft accusation in general. No-one expected Proctor to be hanged, and he chose to leave his good name behind with his death so people think he's died innocently. In effect the people of Salem realise how some people they have accused and hanged may actually be innocent.
Anyway that's just from the top of my head.
These essays I did in Year 10 might help you in terms of main examples to focus on.
By the way, I'm an English (Standard) student.