Student grades rise while exam scores crash 24% — and it takes 2 years to see

a study of 26,000 secondary students in central china found that those relying on ai for homework completed tasks 30% faster and saw an 18% grade increase, yet suffered significant declines in actual learning. while monthly exam scores dropped by 20% within six months, the most severe damage—a 24% drop on high-stakes entrance exams—only became fully visible after two years, indicating short-term studies miss ai's long-term cognitive costs. researchers identified outsourcing as the culprit, noting that 81% of long-term users finished homework too quickly to be learning, whereas students who spent normal time on homework retained their exam performance. social sciences were the hardest hit, with an average 27% decline, compared to smaller drops in stem and language subjects, suggesting critical thinking skills are uniquely vulnerable to ai replacement.