Must
Students must attend school on time
Students must complete homework
Students must actively express their opinions
Students have to be honest when doing tests
Students must be polite to the teacher

Mustn't
You mustn't using phone in class
You mustn't talk in class
You mustn't joking in class
You mustn't play football in school yard
You mustn't throw trash or draw on the walls

You must keep silent in class

You must lisen a lesson

You must throw rubbish in bin in 

You mustn't using phone in class 

You mustn't talk in class 

You mustn't joking in class