How to use an AI checker for teachers fairly
An AI checker for teachers is useful when it helps you decide what to look at more closely. The tool above is our free AI checker: paste a submission and it marks each sentence as reading human or AI, with an overall % human score. What it can't do is tell you who wrote the text.
Treat the score as a reason to look further, never as evidence on its own. Turnitin says the same about its own AI detection: it may misidentify text and should not be the sole basis for adverse actions against a student. That applies to our score too.
A review workflow that's fair to students
- Set expectations early. Tell students at the start of the term what AI use your course allows and how you'll follow up if something looks off.
- Check the submission. Remove names and student IDs, then paste up to 200 words at a time.
- Read the pattern, not only the number. A red introduction in an otherwise green essay is a different situation from red sentences all the way through.
- Compare with what you know. Look at the student's in-class writing and earlier assignments. A sudden change of voice is worth a question. A familiar voice usually isn't.
- Ask about the process. Drafts, notes, outlines and version history show how a piece of writing came together.
- Talk with the student. Ask them to walk you through their argument, a source they used, or a choice they made. People who wrote a text can usually talk about it.
- Follow your school's policy for anything beyond that conversation, and base any decision on the whole picture rather than the score.
False positives: who gets flagged unfairly
AI detectors make mistakes, and the mistakes don't fall evenly. In a 2023 Stanford study by Liang et al., seven widely used GPT detectors classified more than half (61%) of TOEFL essays written by non-native English speakers as AI-generated. The same detectors were near-perfect on essays by US eighth-graders, and 97% of the TOEFL essays were flagged by at least one of them.
The researchers traced this to how detectors score text: simpler, more predictable word choices look more like AI, and people writing in a second language often write that way. OpenAI's guidance for educators raises the same concern for students learning English and for students whose writing is formulaic or concise.
Other writing that can read as AI:
- Work that follows a template closely, such as a five-paragraph essay or a fixed lab report format
- Short answers and summaries of a single source, which are general by nature
- Work polished with grammar or editing tools, which can smooth out a student's own voice
Our detector works best on English. Be especially careful with scores for other languages and for students who are still learning English.
For more on error rates, see how accurate AI detectors are and why human writing gets flagged as AI.
What to look at besides the AI score
| Evidence | What it can show you |
|---|---|
| Drafts and outlines | Whether the work developed over time, with the usual false starts and changes |
| Version history | How the text changed, for example one large paste versus many small edits over several days |
| In-class writing samples | How the student writes without outside help, for comparison |
| A short conversation | Whether the student can explain the argument, the sources and their choices |
| The sources | Whether the cited works exist and say what the essay claims they say |
None of these settles the question alone either. Together they give you a far fairer picture than a percentage.
Student privacy
The text you paste is used only to score it, and we don't store it. Even so, remove names, student numbers and other personal details first, and check whether your school has rules about sharing student work with outside services.
Checking several submissions with a free AI checker for teachers
- One text per check. Paste one student's work at a time. Several submissions in one check would blend into a single score that says nothing about any of them.
- 5 checks a day without an account. A free LumenWrite account gives you more checks every day.
- Long work takes several checks. Each check covers 40 to 200 words, so split longer papers at section breaks.
- Very short work can't be checked fairly. Texts under 40 words aren't scored, and short quiz answers or discussion posts carry little signal anyway.
Students who want to check their own work before they submit it can use the AI detector for essays, which explains how to read a red result and what to do about it.