Reading a submission and recognising a sentence you have seen somewhere before is a familiar experience for any teacher. A plagiarism checker turns that feeling into something you can verify: it finds the web pages that share text with the assignment and shows exactly which fragments match. This page explains how to use it fairly when grading essays, reports and projects.
When a check is useful
- A passage changes style suddenly or uses vocabulary the student does not use elsewhere.
- The text answers a slightly different question from the one you set.
- The formatting is inconsistent, with different fonts or leftovers pasted from a website.
- You want to review a whole set of assignments for a course where copying from the web has been a problem.
How to check an assignment
- Remove the student's name and personal details, or work with an anonymised copy.
- Upload the submitted file (.docx, .pdf, .odt or .txt, up to 10 MB) or paste the text.
- Exclude the reference list and the assignment prompt if the student copied it into the document.
- Run the check and review the share of original text, the sources and the matching fragments.
- Download the PDF of the result if you need it for your records or for a conversation with the student.
Reading the result fairly
A match is not automatically plagiarism. Before drawing conclusions, open each important source and decide which situation you are looking at:
- Correct quotation: quotation marks and a citation are present. This is good academic practice.
- Careless citation: the source is mentioned somewhere, but the borrowed words are not marked as a quotation. Often a skills problem rather than dishonesty.
- Patchwriting: sentences from a source with a few words changed, typical of students who are still learning to paraphrase.
- Copied passages without any credit: the most serious case, especially when it covers a large part of the work.
The share of original text helps you decide where to start, but there is no universal threshold. A short reflection and a literature review cannot be judged by the same number.
What the checker cannot see
The comparison covers pages found on the web. It does not include private university databases, paid journals or other students' unpublished work, so copying between classmates will not show up. If two submissions look alike, compare them side by side yourself. The checker also does not tell you whether a text was written with AI; for that, use the AI detector and treat its result with the same caution.
After the check
Talk to the student before deciding anything. Show them the matching fragments, ask how they took notes and which sources they used, and listen to the explanation. For minor problems, a rewrite with correct citations may teach more than a penalty. For serious cases, follow your institution's procedure and attach the result as supporting information.
Use it for teaching, too
Invite students to check their own drafts before the deadline and to bring the result to class. Seeing their matches next to the original sources is one of the clearest ways to explain the difference between quoting, paraphrasing and copying. The checker is free without registration within limits, and signed-in users and PRO subscribers can check more texts.