Students who use AI score great on homework, but bad on tests: large-scale new study

NY Post Published Aug 19, 2026 Reviewed Aug 20, 2026 ✓ Reviewed by citations.press editors

Students who used AI to write their homework saw their homework scores rise by 18% across all subjects after six months, according to a joint study by David Stromberg of Stockholm University, Victor Lei, and Wu Yanhui of the University of Hong Kong.

18 % · homework scores David Stromberg, Victor Lei, Wu Yanhui, study authors

The time students using AI took to complete each assignment fell from 64 minutes to 45 minutes, according to The Economist.

64 minutes · assignment completion time45 minutes · assignment completion time The Economist, news outlet

Students who used AI for their homework scored 20% lower on exams than classmates who did not use AI, according to the study.

20 % · exam scores study, study authors

The study tracked 27,000 students aged 12 to 18 in China.

27000 · students tracked study, study authors

80% of the students reported using Chinese AI models such as Doubao and DeepSeek, while 20% formed the control group, according to the study.

80 % · students using AI models20 % · control group study, study authors

A survey by Chegg last year found that roughly 80-90% of US undergraduates, 94% of British students, and 93% of German students admitted to using AI in their studies.

at least 80 % · US undergraduatesat most 90 % · US undergraduates94 % · British students93 % · German students Chegg, survey

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Artificial intelligence is great for schoolwork — until you can’t use it on the test, a large-scale new study shows.

Students who used AI to write their homework got better scores and finished their work in record time —but did worse on exams than kids who did things the old-fashioned way, according to new research out of China.

After six months, the students using AI saw their homework scores rise by almost one-fifth (18%) across all subjects, a joint study by David Stromberg of Stockholm University of Victor Lei and Wu Yanhui of the University of Hong Kong found.

All the while, the time they took to complete each assignment dropped from 64 minutes to 45, according to The Economist.

But when it came to exams, students who used AI for their homework scored 20% below their classmates who hadn’t, the study showed.

Experts say the rise of AI may have broken the relationship between homework grades and the amount of knowledge retained for tests.

The study tracked 27,000 students aged 12 to 18 in China, where AI adoption has been turbocharged in recent years.

Some 80% reported using Chinese AI models such as Doubao and DeepSeek, while the remaining 20% formed the control group.

In the West, AI pickup has been even more drastic, with roughly 80-90% of US undergrads, 94% in Britain, and 93% in Germany admitting to using it in their studies, according to a survey last year by ed-tech firm Chegg.

But the evidence doesn’t indicate that AI is inherently a bad thing for students.

In another new study, students at Middlebury College in Vermont were taught an unfamiliar topic either with or without the help of an AI chatbot.

Those using AI scored higher on tests than the control group and had the same advantages when they repeated the task a week later, according to research by Zara Contractor and German Reyes.

“AI can boost learning productivity, but only for those who use the technology intelligently,” reported the Economist.

“Students must resist the temptation to reach for an AI-generated answer before thinking things through for themselves,” added the report.

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