Walk the students through the process shown on the overhead. Discuss why the student in the example decided the topic needed narrowing at each point in the process, and how he went about finding subtopics. Discuss the kinds of questions the student most likely asked himself. Block out the later "evolutionary stages" with a piece of paper until you arrive at them, in order to help the students focus, but also so they feel literally as if they are moving, step-by-step, through the process.
After modelling the one students' narrowing process, ask for a student to volunteer a topic they were thinking of for the essay. Then, as a class, try to think of subtopics and ways to narrow the topic. Have the students ask the volunteer the same kind of questions the modelled student may have, i.e. "What are different kinds of this topic?" "What is my interest in this topic, how am I personally connected?"
After the class has collaboratively narrowed the volunteer student's topic, distribute an Evolution of a Topic Template to each of them to fill out.
Then, after the template is completed, have the students freewrite for a few minutes on the narrowed topic that has evolved.