Brainstorming
The main point is to get your thoughts down on paper. (This is where good notes and annotations come in handy.) Brainstorming is meant to help focus in on an argument. The easiest way to determine what an essay should be about is to figure out where your attention/interest is with the assigned reading material. Once you have ascertained your interest, start narrowing in on a topic/argument.
Brainstorming an Idea
As part of our exploration of the Research Process, we have a section thoroughly investigating what brainstorming is and how to utilize it in order to start your assignment.