As our plagiarism guide notes, “Plagiarism is presenting another person’s ideas, information, expressions, or entire work as one’s own.” Citing sources accurately often requires learning and then carrying out various complex mechanical tasks, from using quotation marks to including an in-text citation to listing the source in the works-cited list. Even professional writers accidentally leave sources out of their works-cited lists (hence the need for editors).

Although we cannot speak to individual instances of source omission, we would encourage teachers to weigh the sum total of a student’s effort to credit a source, as well as the scope of any omissions, the expectations regarding citation that have been communicated to the student, and the student’s level of training, when determining whether the student has plagiarized. Students may simply need a reminder to double-check that all the works they have cited in their paper are included in the works-cited list.