My son has had quite the journey regarding writing challenges ever since Kindergarten. He was identified as gifted, but also earmarked for needing occupational therapy (OT) for handwriting. So in 1st grade, he went to a gifted program and had 1:1 instruction to try to correct his fine-motor issues.
I have a genetic nerve disorder, and perhaps my son is not entirely in the clear. However a neurologist didn't find anything in particular wrong, and so the OT continued until 7th grade.
Due to his continuing difficulty with writing, my son avoided writing like the plague.
Teachers said he could type his answers, and eventually (this is a story in itself!) he was given assisstive technology for writing (a NEO, by the same folks who gave the world Alphasmarts -- a bunch of ex-Apple employees with a vision of helping kids out or something like that....). Basically, his thoughts go much too fast to get down on paper at the speed he needs to write to be legible. So he either holds himself back and his writing is very awkward because he already forgot what he was going to write, or his handwriting degrades to a level that is impossible to read and still lags far far behind the speed of his thoughts.
I suppose that years of being told your handwriting isn't "good enough" and struggling to improve it have taken their toll. The assistive technology came to late and he's already built up considerable resistance to writing. He's quite verbal and able to hold conversations with complex thoughts, abstract thinking, deductive and critical thought, etc. His spelling is spot-on, his grammar is excellent. But don't ask him to write it down. So arguably his ability, but most especially his willingness, to write has suffered considerably.
So I wanted to tackle his writing issues at 3 levels by offering him a "remedial writing class". In his zoned High School they have English 9 and Literacy, both required for 9th Graders. My son's spelling, grammar, and reading abilities are all well above grade level, so I would give him a basic High-School level English class -- covering literature, modern best-sellers, basically all adult reading-level materials, exercises to get him to think about them, put different materials together for new conclusions, research skills, etc. Aside from this literature-heavy class, I would give him a writing class. I've picked out a penmanship book that treats you like an adult: Write Now. The reviews sound great, and I think this is the right way to go on handwriting issues at this point. He doesn't have to be perfect, but he should be able to write checks and fill out forms at the DMV, and that's the type of things I'll have him do to challenge him.
The 2nd aspect that I want him to work on is simply letting words flow through his hands. To this effect, I've borrowed the idea of "Morning Pages" -- a stream-of-consciousness daily journal exercise from Julia Cameron's The Artist's Way. The quality school approach says I will explain the whys to my son, but I still can require that he does the "morning pages" so every day my son will be required to fill 3 pages from a composition notebook with writing. Where he has choice -- 100% choice -- is in the actual content of those pages. This is his own private journal to do with as he will; he can share excerpts if he'd like to. What's not optional is that he writes. I will check it by having him write the date LARGE and LEGIBLE at the top of the page for that day, and then I can see without reading the text under it that he's done his morning pages that day. He could write the same word for 3 full pages, and I will accept it. However, my son's brilliant brain won't stay focused like that for very long. Most likely he'll start out with writing something silly for self-amusement, but I gave him a huge list of "story starters" and journal ideas I found on another website, so that he doesn't have to have anything particular on his mind to do this assignment; he can just pick from the list and start writing. My hunch is that "just writing" will help him break through his internal resistance to writing, help him speed up his hand writing, build up strength and fine-motor skills, improve his basic penmanship (perhaps also his style!), and help him unblock internal emotional blocks if he starts to "trust" the journal and the fact that it is truly a private exercise. Advances in any of those areas would be a breakthrough worth having.
The 3rd "prong" in this is that he needs to not only catch up to the 8th grade writing level but excel into the college writing level domain, as quickly as possible but before the 11th grade for certain. So the most highly recommended book for perfecting essay and expository writing I found is Jensen's Format Writing. I got the book yesterday, and I've taken a good look at it, and decided to re-design some of the scoring sheets to be more in alignment with the "grading" methodology used in The Quality School (via the teachings of William Glasser). So I re-designed the paragraph grading sheet so that instead of grades D (worst) to A (best), there are comments: "You need some help," "It needs work," "You're almost there," and "Perfect!" along with the comment at the bottom of the checklist "You must re-do your paragraph until you have the best score. Please ask for help if you need it!"
If you're interested in this variation on Jensen's Writing Format checklist for your own use, here's a PDF and the Numbers.app worksheet. The forms are 2-up on the page so that you can print and either tear or cut it in half to have 2 checklists. Drafts along with their checklists should be kept for a child's homeschool portfolio. When I've altered the checklists for longer writing assignments, I'll post about them and make sure it's filed under "downloads."