School bell
The ringing of a school bell is a signal that tells a school's students when it is time to go to class in the morning and when it is time to change classes during the day as well as when students are dismissed from school. Typically the first bell tells the students that it is time to report to class and the bell that occurs shortly after that means that the students are late. There may also be a warning bell between the first bell and the late bell.
In some schools it may take the form of a physical bell, usually electrically operated. In other schools it may be a tone, siren, electronic bell sound, a series of chimes, or music played over an intercom. Most schools where people who require sign language more than hearing go to use hand signals.
Criticism
In October 2010 Mackie Academy, in Stonehaven, Kincardineshire took the move to turn off their school bell system, following criticism that the school bells agitated pupils. According to the headteacher the corridors became much quieter after the system was introduced. It was hoped that pupils would take more responsibility for ensuring they arrived on time to lessons. A number of other schools in the United Kingdom have made similar decisions and either partially or completely turned off the school bell system.