In an effort to improve my student's historical references in their expository essays, I have them do this historical research project. It allows students to research not only a person who had an impact on the world, but also important ideas and people of the era. I usually pair students up and have them do a simple expository project after they are done with researching - developing body paragraphs about their person for a prompt. (ex. "Write an essay explaining how one person can have a last impact on others.")
Hope this helps you as much as it has helped me!