Problem:
There are typically four factors for copyright infringement: 1) the amount of the work copied (the more copied the more likely it is to be infringement or the more "key" the copied elements are to the original work, the more likely to be infringement; 2) the nature of the work (the more creative the original work the more likely to be infringement; 3) the purpose of the copies (educational purposes are less likely to be infringement than commercial purposes) and the market effect (if the copies take away from the market for the original it is more likely an infringement).
Please consider the following question: does the practice of quoting from various writers as part of a term paper raise legal or ethical concerns?