A bell signals the start of the first class of the morning at 9 am.

Organized football was a thing of his past, like proms and bells to signal the end of class.

A bell signaled the start of a new three-minute round.

Several minutes went by before the bell signaled a reply.

It was a relief when the bell signaled the end of the period.

The bell signals the start of the class and the students slide into their seats.

She fell asleep abruptly, dreaming no more until the bell signaled the time to wake.

The bell on the machine signaled the incoming fax.

Later it was modified during the industrial revolution to train people for the work force (hence the bells signaling movement).

The bell signaled the different times of the day and therefore controlled the four major gates to the city.