AI Homework Help Boosts Grades but Cuts Exam Scores by 20%

A large-scale study in China finds that students using AI for homework see their assignment grades rise by 18% but their exam scores fall by 20%, raising questions about whether AI tools undermine genuine learning. The research, conducted by David Strömberg of Stockholm University and Victor Lei and Wu Yanhui of the University of Hong Kong, tracked 26,811 students aged 12–18 over 30 months, with about 80% using AI tools like Doubao and DeepSeek Source: La República. After six months, AI users' homework grades improved by 18% and homework time dropped from 64 to 45 minutes, but their exam performance was 20% worse than non-users Source: La Vanguardia. The negative impact was most pronounced among students who completed tasks quickly, while those who spent similar time as non-users saw much smaller losses Source: La República. The study also found that learning losses were greater in social sciences (27%) and STEM (22%) than in languages (17% for English, 9% for Chinese) Source: La Vanguardia. The researchers do not advocate banning AI; instead, they emphasize that the way AI is used matters. Using it to copy answers may improve grades without learning, but using it for explanations and clarifications can act as a personalized tutor Source: La República. This research shifts the debate from whether to prohibit AI to how to prevent it from replacing critical thinking Source: La República.