Outlines are extremely helpful to students to organize their thoughts and ideas for expository writing. Students with a logical learning style will appreciate the use of an outline because it is systematic, which is something that they value. Students with a spatial learning style will also appreciate the use of an expository writing outline because they will be able to see their content in the expository writing in a different way. This can also help students diagnosed with ADHD because the outline will prompt them and refocus their efforts much more quickly. Students with learning disabilities may get overwhelmed by the task of writing an expository essay or a DBQ essay. An expository writing outline can be separated into paragraph sections, making writing a much more reasonable task.
http://www.teacherspayteachers.com/Product/Leveled-Expository-Writing-System-867302 includes an expository writing outline in its leveled writing system.