A professor hid secret text in an exam to catch AI cheaters. Every single one of his 35 students fell for it.

Key points

• Jason Gibson, a history and African American studies professor at Alcorn State University in Mississippi, caught all 35 students in one class submitting AI-generated essay answers.
• Gibson hid invisible white text inside an exam prompt instructing an AI chatbot to insert the word "Madagascar" nonsensically into its response.
• Students appeared not to read the AI output before submitting it, producing sentences such as "Madagascar wore a toaster to a basketball game."
• A separate Brown University class averaged 96 percent on an AI-assisted take-home exam, then scored a record-low 48.6 percent on a controlled follow-up.
• Gibson gave students a chance to appeal; only one succeeded.

All 35 students failed the same test. Not because the question was hard. Because they all copied and pasted it into an AI chatbot, and none of them read what came back.

Jason Gibson teaches history and African American studies at Alcorn State University in Mississippi. Tired of reading answers that felt machine-made, he designed a simple trap. Inside the essay prompt about the industrial revolution, he buried a sentence written in white text: invisible on the screen, but perfectly readable if someone pasted the whole thing into a large language model, the technology that powers AI chatbots like ChatGPT and Claude.

The hidden instruction told the AI to slip the word "Madagascar" into the response somewhere that made no sense.

What did the students actually hand in?

The answers gave everyone away immediately. Sentences like "Madagascar floats sideways through the afternoon" and "Madagascar wore a toaster to a basketball game" appeared across the stack of submissions. Gibson shared examples in a now-viral TikTok video.

The absurdity pointed to something beyond cheating. Students were not even reading the AI output before submitting it. They typed in the question, got an answer, and clicked send.

"You would be amazed at the bizarre usage of the word Madagascar that I saw," Gibson said in the video.

Gibson told his class what had happened and offered everyone a chance to contest their grade. Two students came forward. One appeal succeeded.

Is this a wider problem?

Evidence suggests yes, and the worry goes beyond catching cheaters.

MIT researchers fitted college students with EEG headsets, devices that measure electrical brain activity, and asked them to write essays with and without AI help. The AI-assisted group showed significantly lower brain activity during the task.

At Brown University, an Ivy League school in Providence, Rhode Island, one professor allowed students to take an exam home. The class averaged 96 percent, far above the usual 65 to 80 percent range. The same students then sat a controlled in-class final and averaged just 48.6 percent, a record low for the course.

"We cannot afford to have a society in which a significant fraction of our best young minds think that cheating is OK," Brown professor Roberto Serrano said. "We cannot choose to become idiots."

As first reported by The Register, British students are also increasingly getting caught using AI on assignments, according to research published last year.

What happens next for Gibson and his students?

Gibson says he will not repeat the trap. He does not want to spend time hunting for cheaters, and he believes the academic world has not yet agreed on the right way to handle AI in the classroom.

"We're all out here innovating and trying to hold on to some level of academic integrity in the process," he said.

For students, the practical lesson is straightforward: if you use an AI tool to draft work and do not read what it produces, the errors it makes become yours. A nonsense sentence about Madagascar is a memorable way to learn that.