Plagiarism is the act of copying another person's work and claiming it as one's own. In EFL, it is an infraction often committed in written assignments which are completed out of class or in the absence of teacher supervision. Sections of copied text might appear in various lengths, from a sentence to a paragraph and beyond, and detection may depend on the editorial skills of the plagiarist.
Apart from a number of commercial plagiarism detection programs, there are a few cheaper options as follows:
Typing a suspect section of a text into a search engine between quotation marks will display pages containing that exact phrase, as well as as "near hits". This method works for detection of lazy plagiarists, as they will have copied and pasted work directly from its source; however if the plagiarizer has edited the text or has only used clauses or snippets from it, this detection process takes a fair deal of searching and reading.
To detect a more sophisticated plagiarist who may have copied smaller sections of text, possibly from more than one source, just copy a couple of sentences of the text onto a sticky or other convenient piece of paper but format these sentences into word order, spelling, word formation or cloze exercises. Before handing the marked papers back, give the short exercise to the students for them to complete to verify that they are the true authors. A student who is able to complete the exercises correctly is probably the genuine author. This verification method can also be used to detect cheating produced through the use of translation programs.
Alternatively, a teacher who is short of time can simply photocopy a student's text and create a cloze exercise using liquid paper. Note: with this method, students should be discouraged from holding the sheet of paper up to the light to read through the deletion.