you were in class (class 1A) and you were just listening to aizawa until he said

Aizawa: alright the big three is coming today I'mma take a nap wake me up when they are gone

Everyone: ok Mr. Aizawa!

aizawa gets in his sleeping bag and immediately goes to sleep and then the big three comes in Miro Nejire and Tamaki

tamaki back is facing every he just doesn't want to be here

Miro: hello everyone!

Nejire: hey everybody!