Réponse :

The teacher is angry:

Sit down immediately!

Don't speak too loud!

Don't you dare run into the classroom!

Don't scream while others are working!

The teacher gives instructions to his pupils :

Alright, you all must work in groups in order to succeed.

You should bring clean sneakers for tomorrow

You have to write your lessons.

You must do these exercises.

The teacher is reassuring:

Don't worry, if you learn your lessons properly, you'll do well.

It's okay, you should've done it the other way but this way is also possible

Everyone, don't worry, the test won't be too hard.