To get started on an expository essay, consider a problem or issue of concern related to your chosen topic category (food, education, technology, or race/class/identity) that you would like to “expose” to an audience. The readings from They Say, I Say addressed issues or concerns within the context of these topic categories. I would encourage you to raise a different issue, perhaps one connected in some way to what you wrote about in your narrative essay.
Some questions you should consider addressing in the essay: What is the problem or issue? Why is it a problem/issue? Who is affected by it? How are people affected? When did it become an issue? Where does the issue exist?
Once you have identified a thesis, think about what types of support will help your readers to better understand the viewpoint you are expressing. Will you need to describe a cause/effect relationship between things? Will you need to compare/contrast? Is there anything that must be defined for an average audience?