How do you do limit of topic?

The way to "limit your topic" when you are writing a paper or making a speech is to divide it into several parts, steps, or pieces, and then to write about just one of those. If your teacher tells you to limit your topic even more, then take what you have in your paper or speech--and break it into another, even smaller set of parts, steps, or pieces. And then write about just one of those.