It may be another bell ringing in a primary school but the teachers and students at Whanganui's Mosston School know how to react when that bell sounds on and off for a minute.
It's that intermittent ringing which sounds the alarm and it's something the school family practise with every term.
School principal Michelle Watson said the drills were a vital part of the school year and were used in case the school had unwelcome visitors, there was a fire or an earthquake.
"We never know when any of those situations will arise," Ms Watson said.
And it's during those times that the school goes into lockdown.