"I was so frightened you can't imagine," he said. "You hear the attacks so close and you start to run around like a wounded animal."
Since that day, rocket attacks have become part of the school's daily routine.
Mr Rothstein, 57, is the principal of Sha'ar HaNegev High, in Israel. The school, based 200 metres from the Gaza Strip, is regularly in the path of missile attacks by Hamas militants across the border. The school's 1,200 pupils are forced to take cover in a bomb shelter up to four or five times a day.
Mr Rothstein is currently in England to attend a fundraising dinner for British ORT, an educational charity which has provided temporary classrooms, laptops and equipment, to help the school stay open during the attacks.
The school has suffered direct hits on a number of occasions. Earlier this year, its computer lab was destroyed.
But, Mr Rothstein said, pupils return to lessons after every bomb scare. After only an hour or so they regroup to discuss their reactions to the attack.
"We don't have any choice but to continue," he said. "To continue and continue and hope the next day that there will be peace. It's not a normal time. It changes everything. The staff are much closer to the kids now. We have to be good to them, to listen to them. We're all scared together."
Pupils have responded in different ways. Some are obviously traumatised and are provided with psychological help. For others, stress manifests itself in less-expected ways.
"Sport. The children are talking about sport a lot," said Mr Rothstein. "We're in the country, and there is a lot of open space. But it's dangerous to be outside, far away from the bomb shelter. So they talk about sport instead."
When he took up the headship of Sha'ar HaNegev, 15 years ago, Mr Rothstein, a father of four planned to stay for five years before moving to academe. But he refuses to quit while the attacks are still occurring.
"You feel so responsible," he said. "People trust you. To run away now? Ach, no."
He sees it as his role to keep spirits up, despite the extreme conditions. Occasionally after an attack he will put on a Mickey Mouse hat and visit every classroom. "You have to smile," he said. "It's their childhood. A smile, a joke can do so much in these terrible days."
But he is also taking more concrete steps to ensure that his pupils grow up with a balanced world view. Every year, he and two Palestinian counterparts meet in Istanbul, to compile a citizenship programme which will be taught on both sides of the fortified fence.
"The minute an attack happens, you hate them, you want to kill all of them," Mr Rothstein said. "You ask yourself, why? Why a school? But we're not fighting a war against all Palestinians, just against the fundamentalists.
"The end of war is peace, and peace is about compromise and living together. We have to educate the kids for afterwards. Otherwise, they will have a crazy, pessimistic, fascistic way of thinking. So we need to remind them that we're all human beings. Both sides are human beings."