I'm grading papers, and they're desperate sometimes, and I'm desperate, too.
I need to remind myself that when students are writing to learn, their writing shows it. It's painful for both of us, I'm sure.
If you don't teach writing (or music), you might think that once someone has learned to write a basic sentence, s/he will always be able to produce a basic sentence. But that's not how it works. If a student is grappling with really difficult concepts or learning new material, and trying to write about the new stuff at the same time, basic sentence writing sort of goes to hell.
You can take a perfectly able, wonderful, great student writer, and send them to grad school where they'll study Derrida, and while they're figuring out how to write about Derrida, their writing will go to hell. It's not Derrida's fault, nor the students, that's just how writing is.
If I give my students a short writing assignment to tell me about their family or something, they'll all write pretty much in good sentences. The sentences will work as sentences. But ask them to learn about something really new and difficult and write about it, and most students will have trouble, and their sentences will demonstrate the trouble.
In an ideal world, the students would take that horrid draft and go to the writing center, come to my office hours, or just get really good help peer editing, and that would help them fix the sentence level problems. But, since the students are still (at this level) learning about whatever the topic is, they find revision incredibly difficult. The ones who visited my office a lot with this paper turned out really solid work, unsurprisingly.
But it's also really important to remember that writing about something you're learning is a great way to solidify the learning (just as trying to teach someone about something helps you learn it), so we can't just ask students to write only about stuff that's comfortable.
Still, reading and grading these makes me really want some cookies.