I'm sure that you would have had a check in with your instructor on the progress of your paper, so ydi for not realizing until this late

To quote Sir Raven from The Grim Adventures of Billy and Mandy: "Wait a minute. This is the wrong book! WRONG BOOK!"

Email your professor and tell them what happened, provide proof that you had finished an essay and weren’t just slacking off. Doing so might make them more lenient... well, a D- is better than an F right?

Just tell the truth. Some teachers are considerate enough.

Presumably a re-read of the assignment overview (or a draft submission) would have prevented this?

Attention to detail is good, but attention to the main question is also helpful.

If the book you wrote about is equivalent to the one assigned, your teacher might accept the assignment. But I’d write the real assignment as well, just in case.

Two months for 10 pages? I'm hoping you're in middle school, but then I'm also wondering why you're on FML. It's totally possible to write a quality 10 page paper overnight.

Spoken like a true college student.

Haha, grad student. I wrote the majority of my 100 page thesis (including references, but not including title page, abstract, etc) in about 3 weeks. Granted, that also involved finding and reading 120+ biomedical journal articles for sources, but I'd write each section (between 10-35 pages each) in a day or three.

It took you two months of writing and editing and never once looked back to the book on the subject? I feel like it would be really hard to not reference the source of your assignment for the entirety of an important project like this.

I'm calling fake I can't see any reasonable way this is possible.