The problem lies mostly with style, not content. It's not that
the students lack good ideas, but rather that they have not yet
developed the confident writing voice with which to express
them. Even an essay about school uniforms can be made
entertaining by a strong, unique voice. The process by which
that skill is attained is iterative and beyond the scope of any
singular semester, but I think it begins with a foundational
understanding of grammar and mechanics. Dry as they may seem,
these are the tools with which every great piece of writing is
crafted. Grammar needs to be presented not as a stuffy, boring
set of conventions, but in fact the opposite: a way to artistic
freedom. In the same way that a knowledge of music theory opens
doors for musicians, being well-versed in grammar enables the
writer to fully express himself with authority and legitimacy.
When you have mastery over the rules, you can write anything you
want—and be taken seriously.