A typical paper first surveys the "state of the art" on a topic, then critically analyzes the current condition and offers a novel or creative direction in which research might proceed. Generally, the survey is no more than 2/3 of the paper's length, with at least 1/3 of the paper demonstrating your creative abilities. A sample list of topics from previous students' papers is available.
Be careful in the survey portion to clearly and fully attribute other's work; it's acceptable to do a fair amount of quoting here, but you must be sure to indicate with quotation marks, indenting, and reference marks, when you are quoting versus using your own words. A simple rule of thumb: if you are looking at source text while you are "writing", what you're really doing is quoting.
A typical paper is about 4-5,000 words; at 250-300 words per page, that's about 15-20 pages. If you're substantially under 4,000 words or over 5,000 words, you should probably discuss the situation with the instructor.
To help ensure that you are on the right track, at the end of the third full week of the quarter you are to submit a paper proposal (one paragraph with a five-line outline usually works well) to the instructor either on paper or via e-mail. You should receive an acknowledgment with comments within one week; retransmit otherwise!