The old lady sat down, the three books she had written neatly piled up on the table in front of her. The years five and six pupils of Naima JPS primary school filed in quietly, taking their seats on the chairs and floor. They looked on expectantly and waited for Eva Schloss - famously known as Anne Frank's stepsister - to start her talk.

The room fell silent and she began. In her German accent, the 86-year-old spoke clearly and articulately about her life. She told them that she - Eva Geiringer - had been born in Vienna in 1929 and had fled to Belgium with her brother Heinz and their parents in 1938. There, they felt like unwelcome refugees and so moved to Amsterdam in 1940.

Very soon afterwards, her family went into hiding but were betrayed and sent to Westerbork Transit Camp in Holland, and from there to Auschwitz concentration camp.

She and her mother were liberated by the Soviet Army but her father and brother did not survive. Years later, her mother married Anne Frank's father, Otto.

The nine- and 10-year-olds listened intently as Eva described the tragic life she had led as a girl not much older than themselves, and told them how she'd had to painfully rebuild her shattered life. The children were awestruck to hear about her beloved teenage brother, a poet and artist, who had painted in hiding. Years later, Eva and her mother located the canvases, triggering a flood of heartbreaking memories.

After the talk, as the children stood in line to get a signed copy of one of Eva's books, they had the opportunity to ask her more informal questions. They were clearly moved by her presence and wanted to know as much as time would allow. One 10-year-old boy remarked: "I had never heard of Eva Schloss before today. But now I have met her I will never forget her!"

But the impact of her visit, while significant now, is small compared to what it will be in years to come. The experience is likely to make an indelible, lifelong impression that grows with time as the children turn into adults.

These children are the lucky ones - among the very last generation to have the privilege of seeing and hearing the eye-witness testimony of a concentration-camp survivor.

Today, they are few and far between. Mostly in their 80s and 90s, the numbers are dwindling fast. Sadly, soon there will barely be any survivors left to talk to the next generation of 10-year-olds.

Yes, they have written books and left video testimonies but this is little compared to the real thing - seeing them in body and soul - as they interact with their audiences and share their heartbreaking memories.

But all is not lost. Thanks to advanced technology, a few survivors will "live on" to tell their stories thought interactive holograms.

A few days after the school visit, Eva flew to Los Angeles to tell her story to the New Dimensions in Testimony project at the Shoah Foundation - The Institute for Visual History and Education, based at the University of Southern California. There, she was watched by more than 120 cameras on the Institute for Creative Technology's 3D-capture stage.

This will create a holographic display that makes it appear as if she is in the room with the viewer.

The programme was piloted in 2014 by Holocaust survivor Pinchas Gutter. Eva Schloss is just the sixth person to undertake this cutting-edge interview, joining other survivors, including Renee Firestone and Anita Lasker-Wallfisch.

The USC's Shoah Foundation was founded in 1994 by Steven Spielberg and is dedicated to making audio-visual interviews with survivors and witnesses of the Holocaust and other genocides. It houses nearly 53,000 audio-visual testimonies conducted in 63 countries and in 39 languages.

Eva was interviewed over five long days and made to wear the same clothes each time, so it looked as if the interview had been conducted in one go. During this time, Shoah Foundation executive director Stephen Smith asked her over 1,000 questions about her life before, during and after the Holocaust.

"They asked me about my whole life, about all my experiences," said Eva. "About my family, coping, my feelings, forgiveness, hatred, the Nazis, the size of the camps, the transports. They asked me about the future - what I think will happen. They asked me whatever you can imagine."

On another day, she spent her time making 40 different facial expressions - such as sad, happy, furious, frowning, enquiring, laughing, suspicious. These expressions would be carefully matched to her answers. "It was technically quite amazing," she said. She believes it will stand the test of time and be of great benefit to those wishing to learn about the Holocaust in 50 years' time.

The system uses artificial intelligence - or "natural language technology", to find the most appropriate answer available to a question being asked, enabling a kind of dialogue to take place. "Although she has over a thousand answers on record, she can in fact answer many thousands of questions," explained Smith. He says they are as ready as they can be for the future. "We have planned far enough ahead and now have the data in hand to use in a virtual-reality context. This means that, over the next few years, as the technology further develops, Eva's story will be more interactive and immersive. The world is incredibly lucky that the technology exists in time, to record the last survivors' testimonies in this way."

The holograms will be initially accessible in museums, and eventually through a school platform - IWitness - as an interactive programme.

Closer to home, the National Holocaust Centre and Museum in Nottinghamshire (founded by Stephen Smith and his family) is following suit. Working very closely with the Shoah Foundation, their interactive testimony project is called Telling Their Story to the World.

Filming since last year, they have interviewed survivors Steven Frank, Rudi Oppenheimer, Janine Webber, Martin Stern, Joan Salter, Arek Hersh, Renee Salt and Steven Mendelsson, with Kitty Hart Moxon due next. They want to interview more survivors but that depends upon funding. Following tests and trials, the museum says it hopes it will be ready for the public and schools this spring.

While the technology is keeping the testimonies alive forever, this must still be supported by more conventional education in the classroom. In England, children are taught about the Holocaust within Key Stage three History, as part of the national curriculum. This usually occurs in year nine, for 13- and 14-year-olds. However, many Jewish schools introduce the Holocaust at primary level. Elisheva Simon, a Holocaust teacher at Naima JPS primary school, has customised her own programme for the pupils.

In her interactive lessons, she looks at selected aspects that the children can relate to, including Kristallnacht, the Kindertransport, Anne Frank, and righteous gentiles who risked their lives to save Jews.

She is especially conscious that the children should have a solid foundation in Holocaust education before they move to high school.

"But it is the impact of bringing in survivors for the children to meet that cannot be overestimated, and usually ends up being a highlight of the children's year," she says.

"If children cannot meet these courageous survivors in person, meeting them virtually is the next best thing."