Thesis statement vs. topic sentence
First, it’s good to know what a thesis statement is and what it’s not. A thesis statement is not a topic sentence, although, in some cases it may well be your first sentence. Confused yet? Hopefully not! A topic sentence is the main sentence that outlines what each paragraph in an essay is about, but the thesis statement is the MASTER topic sentence for the entire essay.
Nothing went wrong per se, it’s more likely that no one told you about the expectations of college level writing or you were too nervous at orientation and weren’t listening. Whatever it was, here you are now wondering how to write an essay that’s acceptable in university.