School bell

The ringing of a school bell announces important times to a school's students and staff, such as marking the beginnings and ends of the school day, class periods, and breaks.
When first introduced, schools used physical bells, usually electrically operated. Since then, modern schools have increasingly used non-mechanical bells which may take the form of a tone, siren, electronic bell sound, a series of chimes, or music played over an intercom. In East Asian nations such as China, North Korea and South Korea, the Westminster Chimes pattern is commonly played as the bell, which is also used in some schools internationally.
Schools for the hearing impaired use alternative signaling methods, for example sign language from the teacher and lights that illuminate when the public address/bell is sounding.
File:School Speaker Clock.png|thumb|Combined intercom/clock used for the bell in a modern American high school|alt=

Criticism

In October 2010, Mackie Academy in Stonehaven, Kincardineshire, Scotland, 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 either partially or completely banning the school bell system.

Banning of school bells in Somalia

In April 2010, Al-Shabab–an Islamic militant group that controls large parts of Somalia–ordered school bells banned as they sounded too similar to church bells. Hand claps were then used as an alternative way of signaling that a class was beginning or ending.