I am so lucky to do what I do--to be able to see my students' thinking developing on a daily basis.
We just set independent writing goals for the quarter. Each student selected a genre and one or more areas of his/her craft and mechanics s/he wanted to improve. They will also design their own rubrics (of course, I have to approve them) to think about what quality work in each of the areas means to them.
I have a really strong writer (we'll call her Emily) and I was so grateful to read her goals and rubric. She plans to write fiction. She wants to work on showing not telling and creative sequencing. The thing that got me, though, was specific, straightforward, and insightful her rubric was.
For example, her "A" for showing not telling is "Perfect amount of sensory details but not too many. Same with showing not telling" and her "B" is "Too much showing not telling so story becomes confusing."
For a struggling writer, her rubric would need to be more specific. But she doesn't need it. And she totally gets that you have to have showing AND telling to move a story along.
That is pretty sophisticated stuff.