I highly recommend Institute for Excellence in Writing. It is very good. The recommendation is that you get the teacher training programs, Teaching Writing with Structure and Style and watch it so that you understand the program. You can then teach it to your child OR you can purchase the program Student Writing Intensive Level A (Level A is for 3-5 grades) and have the instructor, Andrew Pudewa, teach your child via DVD. We homeschool and have used this program with delightful results for my son. Check out their website:
www.excellenceinwriting.com