I know my style does not seem like it would come from an undergraduate, but I really did not copy from someone else's work.

A: A few times a year, I suspect that a student has plagiarized, merely from the tone of the writing. Usually, the clues are a switch in tone in the middle of the paper. Then I go hunting for a potential source, in the library or online. (Faculty members can use search engines as easily as students can.)

I am, however, quite fallible in identifying plagiarism. Sometimes, after a search, I decide that there was no plagiarism. That is no wasted effort; I can breathe easier. (You think faculty members like finding plagiarism??) My instincts are generally, but not always, good guides.

If you are ever accused of plagiarism, ask to see the other source your teacher suspects you of plagiarizing from. There is a reasonable requirement of accusers to present prima facia evidence (or evidence that is plausible on the face of it). "I'm sure she copied it" is not sufficient, and teachers are lazy when they accuse without solid documentation. (Feel free, by the way, to (properly!) refer to this page in any such discussion.)

In addition, keeping your notes (every scrap of them) until you receive a paper back can be convincing evidence of the work you did.