 Which is correct, at school or in school, from espressoenglish.net? We actually use both in school and at school for slightly different situations. At school means the person is literally physically inside the school. For example, if you're having a conversation at two o'clock p.m. and someone asks, Where's John? You could say, He's at school. His classes finish at 3.30. He's at school means he's inside the school now. In school means the person is studying in general, usually at college or university, but not necessarily inside the school building at that moment. For example, my husband doesn't have a job because he's in school. He's studying law. I can say this sentence, He's in school, even if my husband is not at school at that exact moment. To improve your grammar, check out my Advanced English Grammar course. It has 45 clear and detailed lessons plus writing tasks with teacher feedback. Click on the link in the video or in the description for more information and to sign up.