SIX million Jews murdered. Experiments conducted on children. Families ripped apart, never to see one another again. The facts and figures of the Holocaust and the atrocities committed at Auschwitz-Birkenau are well-known and can trip off the tongue lightly.

But seeing the camps in Poland first- hand brings one so much closer to the evil that was perpetuated against two thirds of Europe’s Jewish population, along with gipsies, Jehovah’s Witnesses, homosexuals, trades’ unionists and intellectuals.

At Auschwitz, two tonnes of human hair, shorn from the heads of murdered women, is contained in a huge glass case stretching the length of a room. Thousands upon thousands of toothbrushes and combs are on display, along with the same amount of suitcases.

Perhaps most poignant are the children’s shoes, from the tiniest baby’s bootees upwards, testament to the youngsters who were separated from their parents and herded into the gas chambers. There they choked to death on Zyklon B gas over a 20-minute period, before their small corpses were cremated in ovens on an industrial scale.

A trip to Auschwitz-Birkenau leaves one numb at the scale of the slaughter and this was what students from York, Ryedale and East Riding schools put themselves through on a trip organised by the Holocaust Educational Trust. This charity takes teenagers to the concentration and death camps as a way of educating the future generation about the horror to help ensure such atrocities never happen again.

Auschwitz, which was originally built as a military camp, was first on the tour.

The brick buildings look banal enough, but they hide a sinister past with thousands of prisoners kept there at any one time before being sent to their deaths at Birkenau, a mile or so down the road.

Auschwitz also had its own gas chambers, execution wall and punishment cells, where prisoners were starved to death or kept four at a time in a space barely four feet square, leading to suffocation.

Adam Hopper, 16, of Archbishop Holgate School, said the reality of what was done by the Nazis was “gobsmacking”.

“You don’t really realise the extent of the things that happened until you see it. It creates all kind of emotions, it’s hard to contain,” he said.

What is also difficult to comprehend is that the camp’s commander, Rudolf Höss, who was later executed, had a house on the site where he lived a normal family life with his wife and children, while sending youngsters the same age as his own children off to their deaths just a hundred metres away.

Chris McBurnie, 17, of Easingwold School, said the most affecting part for him had been to stand in the gas chambers where thousands of condemned Jews had stood before.

He said: “It was the smell of it. I felt disorientated by it even though I knew it was safe.”

Chris, like many of the students, said he came on the trip to help stop anything similar happening again. He said: “I just thought that the only way to make sure history is not repeated is to fully understand it.”

He, like all the others, will now be preparing assemblies, public displays and talks for schoolmates and those in his community to try to impart a sense of the evil perpetrated at the camp.

Just down the road is Birkenau. While Auschwitz was a concentration and work camp, Birkenau was set up solely for the purpose of murdering as many people as efficiently as possible.

As families disembarked from the train which steamed right into the heart of the camp, they were met on the platform by the SS.

With a flick of the wrist, men, women and children were told to head either to the right or the left. The right meant certain death; the left was for those deemed capable of working until they too had outlived their usefulness.

In this way, fathers, mothers and children saw their loved ones for the final time. There is even an account of a woman who gave birth on the train, only to have her newborn baby ripped from her arms and thrown on to the platform to die.

The most disturbing fact about Birkenau is the size of the place. It stretches over an area of 140 hectares – around half a mile square – while Auschwitz was spread over seven hectares.

In that space, there were hundreds of wooden huts, initially used to stable 50 horses. But in the hands of the Nazis, the huts accommodated up to 1,000 people each. This industrial scale allowed them to murder around 1.1million people at Auschwitz-Birkenau alone.

Much of the site was destroyed by the Germans and then the liberating Russians, who used the huts for firewood. But enough remained to appreciate what the site would have been like. There was also evidence of the lives of those who were killed there.

The Allied Forces discovered that some of the workers at the site had saved the photographs they found in the suitcases of people sent to the site. In all, 1,000 pictures are on display at Birkenau, recording the lives, hopes and dreams of those who were gassed. Most poignantly, the pictures could have come from any era. There are the timeless images of babies photographed on rugs, children playing in gardens, teenagers going on nights out, couples marrying and grandparents with grandchildren.

To say that a visit to Auschwitz-Birkenau is humbling, gut-wrenching, devastating and horrific does not come even close to the strength of emotion that one feels.

Trips to this most evil of places, where the birds now sing and deer live in the neighbouring woods, should be compulsory for everyone.