The most important aspect of teaching any kind of writing is to engage students in the process. Show students examples of well-written persuasive essays. If there is an issue in your city that students are aware of, such as the closing of a public park, present letters to the editor of the newspaper as examples. Connect with the school librarian in search of one of the many funny and engaging picture books that can be used as examples of persuasive writing. Open the lesson with a lively discussion about an important issue in the school, such as dangerous playground equipment, and let students get a feel for arguing their point before presenting the lesson.
If students are to be given a specific topic to write about, the topic should be relevant to them and should be something they feel strongly about, such as why extended recess would be beneficial or why an ice cream bar should be installed in the cafeteria. If students are to choose their own topic, they should be guided through the process of searching for a need, such as having their own room, and compiling a list of reasons that will persuade others to their point of view.
Research shows that cross-curriculum connections are extremely important in the elementary classroom. If you are studying geometry in math, have students choose a polygon and write a persuasive essay about why that polygon is the best. If you're studying your state in social studies, have students write about why their state is the best state. You can connect to the community by having students choose a local current event that is a hot topic and write letters to the editor stating their case, then send a selection of the letters to the newspaper.
Sharing and publishing student work is the important last step in the writing process. Students can present their persuasive essay to the class, followed by discussion and a Q & A, or they can make poster presentations about their topic which are set up around the room for a "gallery walk," in which students spend time walking around looking at each others' work. Essays can be published as a body of work in a book for future classes to use as examples, or they can be mailed to an appropriate recipient, such as a legislator, the newspaper or a family member.