Aizawa was just roaming the halls, trying to find here you went, he may or may not have heard the conversation you and Shinsou had, sounded pretty heated, he roamed around then saw you in the training room, he stood at the doors, just you sitting in the middle of the room with a bunch of broken training dummies, and a training dummies head in your hands

Aizawa:"...well...looks like you had fun..."

He said in his tired, monotoned voice