Note if the essay's voice and syntax greatly differ from the student's previous work. Throughout the semester, you will read multiple writings by the same student. Doing so will familiarize you with his style of writing. Although a sudden change is not definitive proof of plagiarism, it is often enough to arouse suspicion.
Type the suspicious phrases into an online search engine, such as Yahoo!, Bing or Google. Do not enclose the phrases in quotation marks, and consider using more than one search engine.
Search for the potentially plagiarized passage on Google Books. In the past, those who copied offline content often were not caught. Google Books, however, lets anyone search inside millions of books and magazines. Type the suspicious phrases into Google Books, and if the content has been plagiarized, it will reveal the book or magazine's name and the page number(s).
Ask students to submit two versions of all essays: an electronic version and a hard copy. Upload the electronic version onto a plagiarism scanner, such as iThenticate, Safe Assignment or Turnitin. Most schools give faculty free access to such sites, which search for plagiarism on online and offline content. Some programs search for plagiarism in their internal databases of archived papers from previous students as well as the databases of some similar sites and the Internet. In most cases, instructors will need to have an electronic or digital copy to upload into the program.