How to Check an Essay for Plagiarism

Four Methods:What's normal?Finding red flagsChecking for plagiarism onlineTelling your students what you expect

Plagiarism is the act of copying someone's work or ideas and claiming them as your own. Essay plagiarism ranges from copying a paragraph or entire pages from another written source, such as an essay, book, post or article without citing the source used. Checking for plagiarism requires knowing the tricks of the average plagiarist; many are obvious, some less so. This article will teach you what to look for to spot plagiarized work.

Method 1
What's normal?

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    Consider the author's usual work. If you know the writer, what would you normally expect from this person? If the writing is suddenly much better than his usual work, this may be a reason to dig deeper. Of course, if you're blind marking, this step isn't applicable. However, for teachers assessing work directly, it doesn't take long to know what each student is capable of and to spot differences in writing styles.
    • Does this person usually make spelling mistakes but all of a sudden provides good spelling throughout the work?
    • Does this person usually have incoherent or poorly formed concepts, then suddenly presents well formulated statements?
    • Is the work of considerably more length or in-depth analysis than you'd expect from this person?
    • One thing to bear in mind when assessing papers is whether or not an issue was discussed in class. For good researchers and higher level students, this isn't such an issue but for lower level students unaccustomed to or not expected to research more broadly, inclusion of material that is not related to the subject or that goes well beyond class discussion can be a red flag. Of course, it could also be a sign you have a bored and very gifted student in the class, so be discerning.
    • It is possible that the writer has been getting tutoring, has been trying harder or has simply found his or her groove and finally "gets it". The author's usual standard is only one possible indicator to alert you to potential problems; be careful not to overlook the possible good reasons too!
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    Know your subject. Your own knowledge and limitations have an impact on assessing plagiarism. How well do you know the subject area? Do you feel confident that you have read widely or learned enough to be able to spot when someone else has picked up phrases or concepts from another person in the field without using their own words? With experience, you will start to recognize hot spots of plagiarism but even fresh out of college, your own knowledge will help you to recognize when you're reading something that isn't original.

Method 2
Finding red flags

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    Look for inconsistencies or "red flags". Usually when someone is committing plagiarism, they will miss the small differences between their writing and the article, book or essay that they plagiarized from. This type of mistake can make it very obvious that the writer is trying to pass off someone's work off as their own. Some fairly standard red flags of plagiarized work include those outlined in the following steps.
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    Consider the spelling. Spelling can provide a red flag for the assessor if it is inconsistent or switches between regions.
    • Inconsistent spelling: If the same word is spelled differently throughout the essay, this might be an indicator that the writer is copying text in some cases and then cobbling together a few unique passages here and there. Keep in mind that sometimes this might happen where the writer is a poor speller/slack editor and doesn't remember (or care) which spelling is correct.
    • British-English versus American-English (and vice versa): If the author is copying work from a text published in a country where the English used has alternative spellings from your own, this may be a red flag. For example, spellings that use "ou" instead of an "o" such as "colours," or spellings that use a "s" instead of a "z" such as "recognised" should be red flags (and vice versa where American-English isn't standard). In some cases, a student may feel that by using a text or book not published in the local area, that the plagiarism won't be detected. Of course, if your student originated from the country where English is written differently, you need to take this into account.
    • Be aware that if your student has the spell-checker turned on, spelling may not be the red flag you're looking for. It depends on how carefully the student edits, and the more last minute the essay, the less likely such checking will occur.
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    Compare the standard of vocabulary with the expected level of vocabulary of the student. Vocabulary used can be a big giveaway for students unaccustomed to higher level words, particularly during high school. A student with an eighth grade vocabulary using words like "penchant," "beleaguer" or "abase" should be a red flag.
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    Think about the continuity and ease of reading. From your point of view as a reader, does the essay hold together well and is it easy to read? Or, does it seem disjointed, with concepts leaping about here and there and sudden changes in writing style? While some people have a hard time coming to terms with logical sequencing when writing, an essay that has chunks of plagiarized text slipped in here and there, without concern for relevancy or sequence, will often seem much more disconnected and out of the ordinary than someone struggling to get their own ideas into good order. Things to look for include:
    • Sentence fragmentation: If the passage seemed to be going somewhere but then suddenly chops and changes, several times, this may be a red flag that external work has been inserted.
    • Long elaborate sentences that seem out of place: Authors typically have a distinct style (or "voice") when it comes to writing––writing from someone who uses almost exclusively short concise sentences but suddenly changes to add in a few four line complex-compound sentences should be a red flag. Islands of flawlessness in an otherwise badly written paper are signals to be wary!
    • Awkward shifts in point of view: Switching between points of view in a way that seems forced or unnatural may indicate plagiarizing.
    • Weak start and end, amazing middle: (Or, some other form of weak and strong areas.) While this can be a sign of a student struggling to shape an essay logically, it can also be a sign of plagiarism if a student has cut and paste from various different sources. A plagiarizer might write the introduction, cut and paste from several different sources to create the heart of the essay and then write the conclusion. The cut and paste sections will read differently in tone and style from the student's own passages, and the paragraphs will read differently from each other if taken from a variety of sources. The citations will likely be different (a student in a hurry won't have time to be massaging the footnotes or endnotes with any care) and the student's own writing may come across as a lot weaker than the cut and paste portions.
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    Test the punctuation. Punctuation can be a red flag, as many people get it wrong or make it up. If a student has always had issues with punctuation and suddenly begins to use it perfectly, this is a red flag. Where you don't know the person whose work you're assessing, punctuation can still be assessed for disparities. For example, one part of the essay may have appalling punctuation, while another part may suddenly have perfect punctuation. Or, a whole lot of commas and semicolons start appearing in one part of the essay when no other complex punctuation was provided elsewhere in the essay.
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    Check the tense. Any shift in tense of an essay that seems unnatural and isn't in keeping with the student's apparent writing style should be something to look into. Passive tense usage that doesn't fit into the rest of the paragraph is a particularly good indicator, especially since many academic writers have a penchant for using passive text out a desire to sound more authoritative.
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    Look for pronoun inconsistencies. In the case of an "ambiguous" third person, writers tend to commit to using a generic male "he", gender neutral "he/she" or plural "they" to explain themselves. Switches between these ways of expressing third person may be a red flag. Then again, this can be fairly tricky grammatically (and socially), and the writer may simply be confused or fed up with trying to comply with it, so don't overplay this one.
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    Read through the citations. Have the books, articles, online sources, etc., been adequately cited? Or is it obvious that some sources are missing or are poorly cited? In some cases, a student may have taken to citing one author but has plagiarized elements of work of authors cited by the only author the writer bothered to read, hoping desperately that the assessor wouldn't dig any further.
    • Where concepts, ideas or facts have been stated in the words of another, has the writer added a footnote or endnote to back up the statements––or has this been left out?
    • Are quotes included but the citation left out? In some cases, this is about sloppy editing and perhaps forgetfulness, while in other cases, it may be a deliberate attempt to pass off the work as the writer's own.
    • Check the age of the citations. If they're all from some decades past, this may indicate a copied essay––even when a topic covers something solely to do with another era, such as hairstyles of the 70s, there should be at least one recent reference from a more up-to-date writer included. A well-rounded piece of writing will have recent and older dates, or err more on the side of recent analysis for topical matters.
    • Does the citation even exist? In some cases, students make up the citations altogether, or claim that a chapter essay in a book exists, when it doesn't. Perhaps you have access to the book in question and can check. Or, check Google Books or look online for article citations. Knowing when to do this comes with experience and common sense––if you have an inkling that the Journal of Mouse Obstetrics doesn't exist, then check it out.
    • Is it on Wikipedia? You may be surprised how many people think it's okay to quote Wikipedia without further consideration––and definitely without citation!
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    Consider patterns. One very obvious giveaway of plagiarism is when more than one student hands in an essay that reads the same or very similar in content, including placement of paragraphs, headings used and sequence followed. More than two or three people doing this, and there's likely an infestation of the same essay doing the rounds. You'll need to nip this one in the bud by questioning the class as a whole, or following procedures laid down by your school or college.
    • If the cheating is rampant, it may be best to scrap everyone's scores for that assignment and begin over. While this is unfair to those who didn't cheat, some self-regulation among peers can often be one good result of such an action, and hopefully you won't see such a problem arise again.

Method 3
Checking for plagiarism online

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    Start with a simple search engine. If you have suspicions about the work or a portion of it, cut and paste a chunk of the suspicious text or paragraph and paste it into a search engine box. Click return and see what comes back. If the text has been copied either verbatim or fairly closely, it's highly likely that the search engine will return some exact matches. Any online source that is same should appear on the first page of results.
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    Use a "Plagiarism Checker" site. There are numerous sites available to check for plagiarism. Some are free, some charge a small fee––you'll need to read their terms and conditions and understand their limits to work out whether the site can do something for your needs. Basically, look for a site where you can upload or "copy and paste" the entire essay onto the site, and then have the site look for similarities between the essay and other sources. It will pull up any plagiarism it detects.
    • Your school or college may already have a software program in place that is able to do plagiarism checking, in conjunction with the internet or other search sources.
    • Turnitin® is one well known plagiarism checking program.

Method 4
Telling your students what you expect

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    Tell your students about your expectations. It's all very well to jump up and down when plagiarism is spotted but it needs to be handled with care to make it go away for good––at least in your class! You can make a difference to the rate of plagiarism in your class by letting your students know from the outset that you are aware of plagiarism tactics, you know about the essay mill sites and that you do check for plagiarism using software, the internet and your own knowledge.
    • Hold a class about plagiarism early in your class year or semester. Show students what an essay mill site looks like and how you can spot an essay from such a site in the twinkle of an eye (for example, see a round-up of known essay mills at
    • Show students how to avoid plagiarism. Don't just scare them off, as for some students, scare tactics can often result in defiance or a need to get one over you––instead, give them the tools and pathways to writing and researching better and enjoying it a whole lot more. Explore the joy of self-discovered meaning with your students and teach them that it's a good thing to acknowledge how other thinkers have contributed to their own thinking, enabling all of us to build on the thousands of years of great human thinking.


  • Besides explaining what plagiarism is and isn't and how to edit better, many students can benefit from learning about time management. This will enable each student to better juggle all the competing demands of their lives, including sport, different subjects, hobbies, partying, and sleep. If you have the chance, hold a class on time management so that students learn how to avoid the last minute rush to complete an essay (which is a principal cause of plagiarism). Learning the strategies can set them up with a good habit for life and help them to sidestep common problems such as perfectionism and procrastination.
  • Sometimes words that are usually complex or rarely used come into vogue thanks to a movie or song. If a student starts to overuse what was formerly a more complicated word, then popular culture may be the real source, rather than plagiarism!
  • Keep copies of well-written original essays. Some of these may make their way into the hands of future classes and if you have the original copy, it won't take you long to recognize the copying.
  • Sloppy editing skills can always be improved. If this is an element that you think may be contributing to plagiarism (for example, poor citing, bad understanding of how to use quotes, etc.), then do something about it. Hold a class that is focused just on the editing aspects for essays. Test the students at the end to ensure that they have understood the basics well. It can also be helpful to keep an online sheet of ways to overcome plagiarizing, available 24/7 for referral.
  • Plagiarism is often a sign that the writer is out of his or her depth. This is an opportunity for teaching rather than berating or alienating the student. Why does the student seem to be struggling and what can be done about it? Why does the student adamantly believe that he or she is using words of his or her own––what is the gap in understanding here and how can you bridge it? The younger or less experienced the student, the more likely it is that details in understanding have been missed and a remedy would be to find ways to improve this student's understanding of both what plagiarism is and how to find their own words and concepts from within. Don't make avoiding plagiarism sound harder than it needs to be either, or you risk pushing the student into defensiveness.
  • Some students will rabbit on about "information wanting to be free" and that anything on the internet is there for the taking. This sort of talk is rampant but clearly inaccurate and as an educator, you have a role in enlightening your students. Help them to understand that many of them, or their peers, will go on to make a living from words (be it songs, novels, movies, whatever), and that they won't be so excited to claim that their hard work needs to be free then.


  • It will be harder to spot a person who pays someone to write an original essay or do an exam for them. This is plain cheating, and if detected, would usually result in expulsion from the educational institution. While it may be infuriating to think that there are people doing this out there, they will get their comeuppance––it's rather difficult to maintain a high-powered job when you haven't a clue what you're doing or talking about. Check to see whether your institution has checks in place to ensure that the right person turns up to sit exams and use your expectations of the student or class level to guide your own instincts about the work you're reading.
  • Some teachers recommend quick oral tests to uncover plagiarizing students. The problem with this method is that it can scare the pants off an introverted or shy person who has actually done original work but goes blank from fear of speaking up in public or from having to form thoughts quickly. Think twice before assuming anything as a result of quick oral testing––an aggressive approach often reaps what it sows.

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