What is a good topic to bring up in an essay for To Kill a Mockingbird?

I’m writing an essay for To Kill A Mockingbird, and I’m almost done with my first paragraph. (By the way, it has to relate to the theme of Prejudice and Racism in the book.)

Anyways, I’m having trouble coming up with what topic to write the body paragraphs about. You know how a persuasive essay has three main ideas and each body paragraph is about each idea? Well, is this kind of essay supposed to be like that? Or do the paragraphs not have to explain any specific idea singled out from the rest, and the whole essay can just be about prejudice/ racism?