Do you read aloud to her and have her listen to lots of audio books? Sometimes kids need to hear many, many great sentences to be able to produce great sentences. You could pull some sentences from her reading and, instead of having her copy them, have her write a sentence with the same pattern but her own words. That way she has to think through agreement between subject and verb (or whatever she's struggling with) but doesn't have to invent a completely new pattern which adds a level of frustration.

I second the comment on homeschooling high school so it isn't just checking boxes. We seem to have lost some of the love of learning this year (9th grade), and we're just getting the subjects done because we're supposed to for a good transcript. Makes me crazy!

This has been amazingly helpful to me! Thanks for all the hard work, Dicentra, and comments, everyone. My ninth grader has been doing labs alongside the Great Courses DVD lectures, but I knew it was not anywhere near a full course. I've chosen to do Dr. Tang's honors chemistry with the Chang textbook after reading through everything. If anyone has tips for using it, I'd love to hear them!