I have had more than one undergraduate student who I have very strongly suspected of routine plagiarism that I cannot prove. There is a certain style of writing that is just inexplicable except as an effort to avoid plagiarism detection.

I will give an example from a case I was actually able to prove. The student wrote:

Free enterprise prejudice is changing in the current period as another U.S. racial conviction framework at a moment that African Americans are a vigorously urbanized, broadly scattered, and occupationally heterogeneous group; when state arrangement is formally race nonpartisan and focused on anti discrimination endeavors; and when most white Americans lean toward a more volitional and social, rather than innate and organic, translation of blacks' burdened status.

This was clearly an attempt to plagiarize from one of the readings in the course:

Laissez Faire Racism is crystallizing in the current period as a new American racial belief system at a point when African Americans are a heavily urbanized, nationally dispersed and occupationally heterogeneous population; when state policy is formally race-neutral and committed to anti-discrimination; and when most white Americans prefer a more volitional and cultural, as opposed to inherent and biological, interpretation of blacks' disadvantaged status.

This kind of plagiarism is totally missed by SafeAssign, the detection tool that I have access to. When I am able to prove cases like this, it's only with much effort. Of course, I can just give students F for writing incoherently, but I would like to have these students removed from the course. I can only do it if I can prove the plagiarism.

Can anyone recommend any strategies for dealing with this?

EDIT: I of course do try to explain to the student that this is not an appropriate way to paraphrase. They typically say that they understand... and then they do the exact same thing on the next assignment.

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    One possibility you should consider is that the student thinks making sufficiently many changes is not actually plagiarism. (In fact, if there are sufficiently many, it should not be.)
    – Kimball
    Feb 25, 2015 at 9:49
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    I think the question also needs to state whether the student's native language is English (or, in general, the same language that they were asked to write in). I have found the phenomenon described by @Kimball to occur particularly frequently when it was about texts written by non-native speakers of the writing language, as they often seem unable to find a large number of synonymous alternative constructions for a given statement. Hence, their "paraphrasing" resorts to essentially copying sentences from the source material and replacing some words. Feb 25, 2015 at 12:23
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    Did the student properly attribute the source from which the text is "paraphrased"? If not, I think your case is clear-cut. Either way, maybe you can elaborate on why it is difficult to prove these cases. To whom do you have to make your case? In general, what is the process for adjudicating plagiarism cases at your institution? Feb 25, 2015 at 12:32
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    @NateEldredge, indeed part of the motivation behind this question has to do with the institution, a for-profit offering courses online. Plagiarism is especially rampant here and the burden of proof for formally warning a student her is higher then I am used to.
    – Brian Z
    Feb 25, 2015 at 14:37
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    Re "I can just give students F for writing incoherently...": I dunno about that, though. It's not THAT much less coherent than the original :-)
    – jamesqf
    Feb 25, 2015 at 21:18

7 Answers 7


To me it is not obvious that your example is a "clearly an attempt to plagiarize". It looks to me like an attempt to paraphrase. Most students that I see who cheat are too lazy to be bothered to change any words. If the original source was referenced, I would not pursue the academic misconduct route. Instead I would give a poor mark for writing incoherently and not showing any depth of understanding. I might also focus an activity on proper paraphrasing and how paraphrasing does not generally demonstrate depth of understanding.

If the source of the paraphrased/copied material was not referenced, then the situation is more difficult. I would probably first consider if the simple lack of a reference is academic misconduct independent of the copied material. If it is not, then you need to decide if the two actions are academic misconduct. Again, I would probably give the benefit of the doubt and conduct a referencing activity. After the activity, I would let the hammer fall.

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    I see my students doing this from time to time. In their case, I am quite sure they are trying to defeat the plagiarism check (which they later admit 90% of the time). I am amazed to see a student willing to put hours of work to defeat a plagiarism check but they will not spend even 50% of that time to read. Still, I do think it is better to give extra chances along with educating how to do it properly.
    – earthling
    Feb 25, 2015 at 11:56
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    Approaching me it's not clear that your instance is a "transparently a try to copy". It regards to me enjoy a try to paraphrase. The majority of pupils that I see who trick are too lazy to be irritated to rearrange any terms. In case the primordial river-rising was referenced, I timber not chase the school insulate way. Instead I would present a socio-economically disadvantaged mark for inscribing incoherently and concealing any fathoms of understanding. I strength also sharpen image an activity on correct paraphrasing and how paraphrasing does not mainly devildirect fathoms of understanding.
    – komodosp
    Feb 25, 2015 at 14:29
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    @colmde You seem to have some familiarity with this issue ;)
    – Brian Z
    Feb 25, 2015 at 14:45
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    The nature of the passage makes me wonder if there is some sort of software available for automatically (albeit poorly) 'obfuscating' plagiarized text. It would make sense that there is an arms-race of sorts between those making a profit from plagiarism and those making a profit from detecting it.
    – Dan Bryant
    Feb 25, 2015 at 15:39
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    Yeah, that's not paraphrasing to me. Word for word then replace words with bad synonyms is plagiarism, not paraphrasing. Paraphrasing should use normally-used words (with usually a lower vocabulary level if anything) and should have a more compact sentence structure.
    – Joe
    Feb 25, 2015 at 22:34

Moss page states:

it shouldn't matter whether the suspect code was first discovered by Moss or by a human; the case that there was plagiarism should stand on its own.

If you want an automated method of discovering every cheat, wait until the Singularity. Lazy students will always find the way to get past the alarms with minimal work. You can spend months making your software understand synonyms, and they will just spend ten more minutes reordering the sentences.

I think you have sufficient evidence to start the procedures, it doesn't matter it was you or the software who detected it. Anyway, I hope there are not too many individuals like this, in which case you should do something public education at a larger scale.

Also, consider having a talk with the student. Maybe he doesn't think that it is plagiarism.


Well, in this case it sounds like you caught the plagiarism without needing to use the software. How? Because the student plagiarized from one of the course readings, and as it happens you are very familiar with the course readings.

It seems to me that this "human plagiarism catching" can be generalized: you don't have to be able to have software to trawl the internet for copying if you yourself know -- or even have a sufficiently good idea -- which material is likely to be plagiarized. In my experience the average student is remarkably bad at getting academic information from the internet: they don't know enough to rapidly and accurately sift through the deluge, so they hold tight to whatever was high on the first google search screen and succeed or fail accordingly. If you are concerned about plagiarism, I think it would be time well spent to search the internet before making the assignment and bookmark the most plausible sources to be plagiarized. This won't catch everyone, but then again nothing will. If you feel strongly enough, you might even design some initial assignments as "plagiarism bait". As long as your goal is to teach your students right and wrong rather than a priori to get them in trouble, I think this is an entirely justifiable thing to do. Also showing someone that they have already gotten caught and gotten in some trouble can be a great motivator for keeping their nose clean in the future (or, sure, digging much deeper in their dishonesty, but again one has to play the percentages here).

Good luck. I don't work in a field in which plagiarism in papers is common -- I am a mathematician -- and the idea that university students regularly commit such dishonorable acts disgusts me. Anyone who wants to take a harder line (and of course who informs and educates the students in advance) has my full support.

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    I'll disagree with one part of this comment. Plagiarism of solutions to exercises is relatively common in mathematics at the undergraduate and graduate levels. In my experience students will often attempt to copy solutions to homework exercises from solution manuals (some of which may have been prepared by third parties that the author and instructor don't know about.) Some ways to stop this include modifying textbook problems before you assign them to students or assigning exercises drawn from other sources or just writing your own exercises. Feb 25, 2015 at 14:31
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    @Brian Borchers: Yeah, I have to agree with you. Copying exercises from textbooks isn't quite the same as plagiarizing a paper, e.g. because the exercises and their solutions often appear in a very similar form across many textbooks. But believe me, I am well aware that this phenomenon occurs and have adapted to its existence in several ways. (For instance, in courses at the advanced undergraduate level and beyond I always write my own exercise sets.) Feb 25, 2015 at 15:18
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    @Brian Borchers: I really don't see how you can show plagiarizism/copying in most math or science problems. There is, presumably, only one correct answer, and only a very limited (often only one) way to obtain that answer.
    – jamesqf
    Feb 25, 2015 at 18:50
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    @jamesqf: At least as soon as students are responsible for proofs, they are also responsible for producing clear, coherent arguments (I would argue that this comes earlier but it seems many institutions disagree with me). Then you immediately end up with the multiplicity of stylistic possibilities present in any discipline outside the "hard sciences". Within two or three assignments, I (as a TA) can usually detect a student's emerging voice, and it is very clear to me when it changes abruptly. I don't know a way to present quick evidence of copying, but with time, it can be shown convincingly. Feb 25, 2015 at 20:34
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    @jamesqf: Even with purely computational problems some cases of copying are obvious. My favorite, from an in-class exam. The source paper had a mostly correct solution with one computational error that resulted in a distinctly odd answer, but the student in question had rather bad handwriting. The student copying from behind and off to one side, writing what he thought he saw, turned it into nonsense ‘leading to’ the same odd answer. The answer was odd enough to ring a bell when I saw it the second time, and one look at the papers made all clear, especially when I recalled where they’d sat. Feb 26, 2015 at 20:57

If I was the instructor...

I would first strike out all wordiness: e.g. in the current period; at a moment; or... at the present time etc. There are numerous "wordy" lists available on the Internet that you can refer to for this part.

Then, to detect hard to prove plagiarism, I would search only on significant or weighty phrases and ignore the adjective fluff--except for superlatives and qualifiers (few, most, many--which many students/people have trouble changing into different words).

Focus on phrases that wouldn't seem to matter to a student who is copying, rather than comprehending/understanding what he/she reads... like "most people", "few people", "many Americans", "few Blacks", etc. Also focus on the "meat"--phrases that students would strive to retain because it sounds more sophisticated or more academic.

So from the student example, I would pull out phrases like these, adding plus signs between them: U.S. racial+urbanized+occupationally heterogeneous+anti discrimination+most white Americans+blacks'+status [blacks' as plural possessive]

Put only that string of select words and phrases into Google.

The second Google hit shows enough resemblance--all the words are present. That hit goes to Google Books: Racial Attitudes in the 1990s: Continuity and Change, pg. 18 edited by Steven A. Tuch, Jack K. Martin

In other words, don't take a student's full sentence to use when checking Google. Instead, pull out phrases that sound like the student is a professor-wannabe, words the student would rarely or very rarely string together based on the student's age, college level, past writing assignments, past academic performance, speaking habits, etc. For example, if a 19 yr old with a C-average turned in that mess, I'd immediately think "plagiarized!"

For in class teaching strategies, professors might assign speaking presentations early in the course. As each student presents orally, write on an index card the student's style and speaking level. e.g. Notes like: uses simple words; no sophistication; uses few/too many adjectives; uses good analogies; noun/pronoun-verb conflicts like "He run" instead of "He ran". The cards will be a reference for you when evaluating writing assignments throughout the course.

A second teaching strategy: Print out a paragraph from a textbook, say 5 sentences long, with a copy for each student. Make it 'count'--assign grades for this exercise. Have them silently read it. Instructions: Turn the paper over and don't look at it again. In 3 to 4 sentences (reduced from 5) write "in your own words" what the author said. You may not use any significant phrases or adjectives from the original text except identifiers like age, gender, nationality, etc. (Men; women; middle-aged; American; Canadian, etc.) You may not simply replace words in the original with synonyms. [Alternate assignment: Same instructions but they may refer to the original and give permission to reuse only 3 significant words or phrases from the original version. If more than 3 are used, it will result in an F for the exercise.]

Teaching strategy #3: Review good class note-taking. Specifically instruct the students to take notes for this class. Teach for 15-20 minutes. Stop and pick several students to refer to their notes and re-tell the class the main points you made but they must put the ideas into complete sentences. Their version must re-tell what you taught, as closely as possible. After several students share their retelling, review with the class how "important pieces" in lecture notetaking is similar to the task of "paraphrasing" points from texts. Talk about how hearing significant pieces from your lecture for notetaking purposes uses the same skills they need to also 'hear' /listen for significant words/phrases in texts. Discuss why they must use "phrase quotes" on significant pieces when paraphrasing for a writing assignment, in addition to sentence quotes. And discuss attribution for both.

I enjoyed writing this and hope it sparks further ideas.

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    Be careful with comparing oral and written texts style. Foreign students tend to be better at writing than their oral, while native speakers tend to be better at oral than writing, but even this is not certain. Also, for most people, oral tends to use shorter, simpler words than written (one of the best way to detect if someone is presenting by reading off text vs referring to cue cards is to see how much they ramble with long sentences not normally intelligible in spoken language). You'll have a really hard time using your oral reading to detect or prove plagiarism.
    – Lie Ryan
    Feb 26, 2015 at 0:39

It looks like this student was aware of the "five consecutive word plagiarism rule."

S/he is copying strings of four words or so, and taking care to change the fifth (and maybe sixth) in sequence, (hence the "bad synonyms") then goes back to copying another "string," etc. Assuming that you know the underlying material, that's how to detect it.

As explained in other answers to my question, plagiarism consists of "lifting ideas, plots" as opposed to merely words. Your student is violating the spirit of anti-plagiarism rules while conforming to the letter (or trying to).

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    "plagiarism consists of copying ideas, as opposed to merely words." - Citation needed. That's not my understanding. One way to improve this answer might be to remove that erroneous claim, and then answer the original question about how to prove this kind of plagiarism.
    – D.W.
    Feb 25, 2015 at 23:03
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    @D.W. See Lauren Ipsum's answer in the link. I replaced an earlier link with the "correct" one. Lauren is a professional editor, and the highest ranked member of the Writers' SE site.
    – Tom Au
    Feb 25, 2015 at 23:10
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    I suspect you have mis-paraphrased Lauren Ipsum's answer in the process of re-wording it. I read Lauren Ipsum's answer as saying that copying words can constitute plagiarism; and that copying ideas can also constitute plagiarism. I'm not sure what you are trying to say in the last paragraph of your answer, or how it answers the original question.
    – D.W.
    Feb 25, 2015 at 23:12

Detecting plagiarism has two parts. The first part is to find a possible match, and the second part is to compare the two works. Plagiarism is likely when a work is very similar to one specific prior work, and much less similar to other works.

The problem with SafeAssign here is unknown. It could be that it fails to find a possible match, or it might find the two works dissimilar.

We recognize the two paragraphs from the question as similar because the sentence structures are almost identical, many words are identical, and where the words differ they're synonyms. But you had the advantage of recognizing which text it came from. This part could in fact be automated without major problems.

The main challenge for automated plagiarism detection is the selection of similar candidates. This probably needs to be done on multiple scales. First, transform the text by doing a grammar analysis. Replace any noun by literally "noun", any verb by "verb" etc, and see if you now find long matches. Secondly, replace all words by canonical synonyms or hypernyms and check for matches of smaller length. (It doesn't matter if the text becomes hard to understand or somewhat nonsensical). Finally, for the smallest scale, just sort lists or enumerations.

Taking one step back, how would a plagiarism detector come up with likely candidates in the first place? A good method is to realize that documents about the same subject will typically both use fairly uncommon words. As a simple example, the word "God" is rather common in theological works and much less so in theoretical chemistry. This process will still work as an effective filter for the pair given in the question - both are trivially recognized as sociological works by their word choice alone (disregarding any sentence structure).


I give an oral quiz to each of my students, not to find plagiarism but to assess understanding of the material. I pay close attention when a student of whom I believe to have "paraphrased" their entire paper. I'm a science teacher which puts me at an advantage. if the student can't comment on any of the challenging concepts, I find it suspicious.

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    Welcome to Academia.SE! Can you elaborate on what you do when the student cannot comment on the challenging concepts? The OP is already at the "suspicious" stage: I believe the question is more about how to deal with these students.
    – wimi
    Nov 17, 2019 at 19:21

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