Having used a variety of writing curricula over the years, I am inclined to believe you have to find an author who most closely aligns with your style of teaching and philosophy since people approach writing through a variety of avenues.
Some authors prefer to be formal and have specific elements that are to be present in each of the piece that is written. If that is your style and thinking, then here are a few programs to research:
Institute for Excellence in Writing, Andrew Pudewa This program is tried and true with a DVD set to help you understand and teach writing. Areas of study include: outlining, summarizing, research papers, essay writing, and creative writing. Multi -age and multi-grade level, beginning in elementary and continuing through senior high school, this program will serve your student well in communicating in a clear and concise manner. Essay writing will be a breeze and research papers will not be a daunting task since students are taught how to do this easily with this program.
Writing Strands, Dave Marks, is a veteran teacher and home school dad created a multi-grade program for students. The four strands of writing (argumentative, explanatory, creative, and report writing) are explained and modeled for students. Short lessons for students to practice after each lesson with humor are sprinkled throughout the lessons.
Are you interested in an incremental writing program? Two that I recommend are Jump In and Write Shop.
Jump In is a writing program from Apologia that can walk your writer through a step-by-step process of even the most daunting writing tasks. The writing steps are small with a practice section for the students after each skill is taught. The process is explained in a conversational manner that a junior high student could read it on their own and you, the teacher, can discuss and monitor the work that is being produced. Students of various writing levels and grades will enjoy using this curriculum.
Write Shop has programs beginning in kindergarten. The nice thing about the primary books is that you can do them orally with your beginning writers. Having used the middle school program, students enjoy the topics they are given to explore. Giving students the opportunity each time to write about something they enjoy enhances the program and involves the student even more in the writing process.
Are you looking for online programs?
The Potter’s School has classes for writing beginning with 5th grade and continuing through 12th grade. Not only can your student take a writing class, but they have a wide selection of classes in every academic area. There are summer and year round classes from which to choose. In the past have worked with several of the outstanding tutors and I highly recommend this program.
Write at Home can either be used as an a la carte program that your student submits individual papers to be read and graded by a teacher, or your child may enroll in a full-time class beginning in the fall. Their classes begin with middle school (5th grade) and continue through 12th grade. One of my friends used it exclusively for their a la cart program and her daughter loved it.
Home2teach offers high quality, challenging, college-prep online writing classes to homeschoolers ages 8 to 18 world-wide. While I have not used this program, it does look like a terrific option for students.
If you have found a program that I have not discussed here, please leave a comment.