This is cool, but I think a touch too much for 4th graders. Middle school writing, I think.
Expository Thinking Map
I would use these writing prompts to have students practice expository writing. I would write at the top of the sheet "Write to explain..." and let the students choose their writing prompt.
Expository Writing Hooks Anchor Chart
Expository Writing Anchor Chart | Expository vs. Narrative Compositions
Adventures of a Future Teacher: Expository Writing Anchor Chart elementaryeducati...
Expository Writing Freebie, includes anchor charts, draft book, teacher draft book, and brainstorming pages
Use this rubric to easily and consistently evaluate your students' expository writing. $1
Having expository transitions explicitly written in step-by-step format helps facilitate direction for ESOL students.