Answer: The author believes that writing instruction should start with narrative because it is most personal and familiar. Then the students should move to expository writing and, finally, to persuasive writing.
Comment: An interesting sequence in types of writing. Keep in mind that narrative is often a big part of expository and even of persuasive writing. RayS.
Title: “Narrative as a Springboard for Expository and Persuasive Writing: James Moffett Revisited.” Barbara J. Radcliffe. Voices from the Middle (March 2012), 18-24.