LISBON- In more and more public buildings, you'll find a device that can make a life-saving difference if someone goes into cardiac arrest. It's called an automatic external defibrillator...or A-E-D for short.

They are simple to use, but even so many experts say you should also know C-P-R to use along with the automatic devices.

Every two years, Lisbon's school system puts on an A-E-D training session for staff. On Thursday, 28 teachers and administrators took part in the certification training. That's about half the entire school system staff.

Organizer Julie Light, the school nurse, said the A-E-D's practically run themselves...adding "it's so easy to follow, anybody can learn it. I think the last study I read was that a sixth grader can learn how to do this in six minutes."

Lisbon schools provides on A-E-D device located in a hallway. If someone quits breathing while at the schools...one staffer would begin basic C-P-R while others call for help and bring the automatic defibrillator.

The machine analyzes the heart rhythm, gives simple instructions and, if needed, would deliver an electric jolt to the heart.

Lisbon staffers have never delivered a jolt for real. But the device was made ready twice when both a student and a teachers collapsed. However, those were not cardiac arrest cases and the machine did not deliver a shock.

Still, teachers undergoing the training say having it within easy reach, and having people specifically trained, provides a sense of security.