Every student should be entirely clear what the rules are for using sources properly in written assignments.
Sometimes students go astray in the way they use source material in papers. This can happen with international students (who may be used to a different set of norms about papers) and also with American students. In many years of teaching I have come across quite a few problems like this, and I take it very seriously. The scenario that is most important to avoid is committing plagiarism and failing the class. But it’s also important to develop good habits of note-taking and citation, and to understand in general what the expectations are.
A paper, or anything you submit for a class or in a professional academic context, must be your own, original work. But in creating that work, you will be drawing on sources, many or all of which are things that others have written or collected.
The sources for all the information you present in your paper should be documented. It is not enough just to list reference material in a bibliography at the end of the paper. A footnote, endnote, or in-text citation should follow soon after any fact, quotation, idea, argument, or other material that you obtained from a source. It is best to use one of the citation styles approved by the Politics Department.
Though it is not necessary, graduate students in particular may wish to use bibliographic database software to help you manage sources, such as Zotero (free) or EndNote (costs money).
Any material that comes verbatim from a source should be put in quotation marks and cited, including the page number — and quotes should be used sparingly.
Anything that comes from a source but that you are not quoting should be rendered in your own words (not the source’s words or something close to them.) The source material should still be cited, including the page number.
When you are taking notes, make sure that it’s very clear in your notes what are your words and what are words taken verbatim from a source. Do not copy source material directly into a paper that you are preparing unless it is one of the very occasional quotations that you might employ, as mentioned above.
Those are the basics. I recommend that you consult this inexpensive book when you have a chance: Gordon Harvey, Writing with Sources: A Guide for Students (2nd edn.; Indianapolis, Ind.: Hackett Pub. Co., 2008). It was written specifically for undergraduates at Harvard but it applies anywhere. It’s inspired; it deals with many subjects related to the writing of papers; and it’s a pleasure to read. Apparently the author has made a PDF copy available.