As an English teacher, I’ve had numerous conversations with college professors who lament the writing skills of their first year students. But not all writing. Most students are capable of solid expository writing. It’s their skill with persuasive writing that’s the problem. Specifically, they’re weak at writing a thesis statement that can be argued.
I spend three years teaching my high school students how to write a persuasive essay. For many students, it takes that long. (And I’m lucky to have them that long in my school.)
A very good article on the differences in writing an essay versus writing a blog post.