A built-in Master Clock controls and synchronizes all digital and analog secondary clocks, ensuring all clocks in a facility display the correct time. The Master Clock can control multiple events throughout the facility, such as class change signaling, and automatically adjusts for seasonal events, holidays, and daylight-savings time. Digital clocks can display messages (e.g. "Bell") from the Master Clock to provide visual indication of events. Messages can be coded to discreetly convey matters of concern to staff, such as an unlocked open door Scrolling messaging capability is also provided. Messages can be activated/deactivated automatically or manually.