Should every paragraph have a topic sentence?
In academic writing, almost always, and at the start. It lets a reader follow the argument by reading first sentences, which is exactly how graders skim a long document. Delaying the point for effect works in other kinds of writing and rarely helps here.
This comes up on Paragraph Structure, where it is answered in the context of the work itself.
Not what you asked?
Ask us the actual question
Send the draft, the rubric or the score report with it. You get a real answer and a price before you commit to anything.