Should teenagers be treated as adults

It actually depends on the teen. for example if the teen is very independent and responsible, then you should treat them like an adult but if the teen is irresponsible and is a bit immature, that means that they are not ready to be treated like an adult because they are not mature enough to handle more demanding responsibilities.

It actually depends on the teen                                                                                                        

The bell is just a signal that the set time of the end of class is passing. the teacher lets you know when it's okay to leave.