School principal Mohammad Jaser presses a button to open the intercom system and makes a routine announcement.
"The Israeli army has been spotted near the premises," Jaser says, his voice blaring from speakers and into the classrooms of the al-Sawiyeh al-Lebban school near Nablus in the northern West Bank last month.
"Stay inside your classrooms, away from the windows, and lock the doors," he instructs the students. "Prepare for an evacuation."
The students and teachers at the mixed school, located between the villages of al-Sawiyeh and al-Lebban, have been trained to respond to incidents like this.