Exams test more than just subject knowledge—they also test how clearly you can express what you know. Even students who understand the material well often lose marks due to common grammar mistakes students make in exams. Poor grammar can confuse examiners, weaken arguments, and make answers harder to follow. In this guide, we’ll look at the most frequent student grammar mistakes in exams, explain why they happen, and show how students can avoid them with better habits and AI grammar checker tools.