It is worth the effort for the instructor to establish the plagiarism rules and enforce the consequence if work is plagiarized. Mr. Lazara says of his investigations. I frequently check sources. In one case, it took me upwards of 2 hours to catch someone by surfing the Internet. In another case it took a trip to the library, and in still another, it required that I obtain a copy of the textbook he used in a previous course on that topic.
Proactive enforcement is the best method for reducing plagiarism.
Once students know the instructor will not let plagiarism pass, word gets around quickly that the instructor checks sources. A good teaching example of disciplinary action is evident in a recent example of Mr. Lazara. I could tell that the material was presented in a highly technical style with the jargon of the field and presented in a form that was well beyond the writing competency level displayed by the student in past work. It took me about an hour to prove it since I checked Americana and Encarta first, suspecting by the style of writing that it was taken from an encyclopedia. So, I failed the paper and filed formal plagiarism charges that included a copy of the plagiarized materials attached to a copy of the original materials from which they were copied.