A Student turned in an essay answer to a question I haven't asked yet. What to do? A student turned in a bunch of homework assignments, poorly organized and many not labeled.  One of them was on a topic for several weeks from now.  The student turned in a short essay for the assignment, which I have not given.  

Notes:
Most of the course material was prepared by someone else and is normally used by several of us adjuncts.
I've taught this course prior.  

English is not the student's primary language (interesting since the essays turned in are in very good English...).  

Since I haven't given the assignment, is it plagiarism?  (What was turned in is straight up a copy of an internet source.)  

Do I report them to the Chair/Dean for plagiarism?
This is clear cut plagiarism. And not only is it plagiarism, it is also very poorly conducted plagiarism, which is a bit worse in my book, since it indicates that the student does not even takes studying seriously enough to read through the assignments and understand what he/she is plagiarizing.

Your university surely has guidelines. If you don't know the guidelines, you can ask the person responsible for undergraduate education at your institution, which will probably also be the person you should report to.

And let me just add one final thing: You don't do the student any favors by not reporting. Plagiarism exploits the mutual trust there always needs to be when teaching, and this is harmful for university education as such. Plagiarism and cheating should therefore always have consequences.