AMNA NAWAZ: Well, it's back-to-school season.

And, last night, we brought you a report on Israeli children displaced from their homes and schools by the war and violence.

But, in Gaza, 625,000 children have no school to return to at all.

Most of Gaza's 560 schools have been damaged or destroyed.

More than half have been directly hit by Israeli forces, who say schools have been used as shelter by Hamas militants.

As Nick Schifrin reports with producer Shams Odeh, in Gaza, the few remaining schools are now shelters for the displaced.

NICK SCHIFRIN: In Deir al Balah in Central Gaza, the classroom is a tent and the students displaced children of war, proud to contribute, eager to learn in a class, rather than from the conflict they have been forced to endure.

TAHA IBRAHIM, Volunteer Teacher (through translator): We're trying to provide relief for children through education and play so they feel better mentally.

NICK SCHIFRIN: Taha Ibrahim is an elementary school teacher, himself displaced, and a volunteer with a French-sponsored program for kids.

TAHA IBRAHIM (through translator): As educators, we're trying to help students remember what they have learned and at the same time try and cheer them up and relieve them from the pressure they're under, despite ongoing bombing and displacement.

NICK SCHIFRIN: In a neighboring tent, 8-year-old triplets Lana, Batul and Line Abu Asee, with their younger sister, Bisan, have a message for the kids around the world starting school this week.

BATUL ABU ASEE, 8 Years Old (through translator): We're supposed to go to school.

Everyone is going back to school, except us in Gaza.

You're so lucky.

NICK SCHIFRIN: They have lost their home and been displaced multiple times, but have held on to their dreams.

LANA ABU ASEE, 8 Years Old (through translator): I wanted to be a doctor because I want to help people who aren't feeling well.

BATUL ABU ASEE (through translator): When I grow up, I want to be a teacher so I can teach kids and they can learn.

NICK SCHIFRIN: And so the triplets leave their canvas home in the Al-Zawayda camp, which has been their refuge for months, and cross just a few steps over the sand to arrive at their canvas school.

Tent classrooms like these are all that Gaza's children have in a war where the U.N. says more than 9,500 children enrolled in schools have been killed.

Gazans say the entire educational infrastructure has been eviscerated.

The U.N. says at least 85 percent of Gaza's schools have been directly hit or damaged.

And in this war and in every war in Gaza, U.N. schools transformed shelters for nearly two million displaced, like the Abu Himasa (ph) School in al-Bureij camp, classrooms once filled with students now home to families with nowhere else to go, clothes, rather than chalk, dishes, rather than drawings, a kitchen and a bedroom all piled up in a corner.

ONANA ABU AL-KHAIR, University Student (through translator): When we used to go to school, they would teach us that school is our second home, but now it is, in fact, our only home.

NICK SCHIFRIN: Onana Abu Al-Khair was studying to be a dentist at one of Gaza's top schools, Al-Azhar University, seen here before the war and today.

The U.N. says all of Gaza's 12 universities have been damaged or destroyed.

Israel blames Hamas for living in and fighting from residential buildings and using schools turned shelters as cover.

Despite it all, Onana Abu Al-Khair tries not to forget what she's learned or what she's lost.

ONANA ABU AL-KHAIR (through translator): Gaza was beautiful, with its people, busy streets and food.

We want to go back to that because we cannot get used to the situation we're in right now.

We are not resilient.

We are forced and obliged to live this way.

NICK SCHIFRIN: Her mother, Suhair: SUHAIR ABU AL-KHAIR, Mother of Onana (through translator): It's as if we're dying slowly while still alive.

We want these young kids and students whose life was taken away from them to be able to live again, so they can get up, get dressed, wear their uniforms, eat breakfast and go to school, see their teachers and their friends, study and excel.

NICK SCHIFRIN: But those are dreams deferred.

UNICEF estimates all of Gaza's children, one million people, need mental health and psychosocial support.

They have seen too much and had to grow up too fast.

Maryam Al Nabahin is 4.

MARYAM AL NABAHIN, 4 Years Old (through translator): Our home was bombed and there were injured people everywhere.

There were rocks, little tiny rocks.

I wish I could go to kindergarten, for the war to end and have a new home.

NICK SCHIFRIN: But, for so many, there's no going back, back home, back to school, back to what childhood is supposed to be.

For the "PBS News Hour," I'm Nick Schifrin.