Every year, it seems that I try a new approach, and seldom does it accomplish what I want it to (improvement in student writing). I'm no expert, and a cursory read of my posts will probably produce scores of errors which would infuriate devout grammarians, but I do believe that by high school, there is merit in helping students see the "interior structure" of the language they use. Knowing that structure, hopefully, helps the strong writers refine and the weak writers give name and therefore understanding to their weaknesses.
This year, my rocky relationship with grammar led me to make a dangerous decision. Last semester, I did not teach it. At all. I responded to student writing and offered revision advice, but I didn't instruct about anything grammar-related. Instead, we focused on higher order rhetorical arrangement (argument, essay, paragraph). Over the course of the semester, I proved to my students through lessons, assessments, and feedback that I knew what I was talking about and knew how to help them. They started intentionally responding to my feedback and advice, and in reflections on their writing processes, I repeatedly saw references to "I never knew this before" or "now I understand." A strange thing happened, then, a few weeks ago when I finally, grudgingly and anticipating epic futility, settled into my hardcore grammar lessons and curriculum.