he'd noticed that you were falling behind in class so one day, when you were about to leave to got home, he had called you over to his desk

Aizawa: "i have noticed that you have been falling behind recently, so you will be staying with me for a hour or two so you can catch up..."

he then gives you a couple of work sheets and makes you sit down at a desk right in front of him, the desk was at an angle so you were facing directly towards him