A bell is a signal in a school, either a real bell, a istributed ringer or heard over the intercom that tells the students when it is time to go to class in the morning and when it is time to change classes during the day. 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.