A letter to the editor is a great idea.
I might also suggest that even major newspapers usually have a "guest editorial" piece about some burning issue each day or each week. If she has a cause to write about, it's possible she could get that spot. They usually include a photo of the guest editor, too, and I have seen pieces by articulate kids published there in more than one newspaper in more than one city.
She could also offer to write a "kids around town" article once a month for the education editor. If she can find a human interest story and write it from a uniquely kid's perspective, it might be something that would interest them if she has the writing skills to pull it off.
