Wednesday: We arrive at Nieuwpoort-am-Zee in Belgian Flanders. It’s the northern-most tip of the 450-mile-long Western Front. Tomorrow we start our two-day coach tour of the First World War battlefields: four teachers, 47 GCSE students from Chesham High School in Buckinghamshire, and myself.

Eighty years since the war, and the names on our itinerary still resonate: the Somme, Ypres, Vimy Ridge, Passchendaele. How will we feel treading those fields where war was shown at its most futile? Teachers Neil DeMarco and Nick Burkitt are veterans of such trips: but what lessons will the younger generation learn in this most poignant of classrooms?

Thursday: To France, and the Somme. A brief stop at Delville Wood, scene of the last cavalry charge in British history. Fierce fighting here: the troops called it Devil’s Wood. Now lush and tranquil, with a memorial to the South African dead.

Over the road, our first cemetery. Immaculate lawns and flower beds, row upon row of white gravestones. Many have no names, no unit badges: just the simple inscription, “known unto God”. A visitors’ book records today’s reactions: “Our third visit, and still it’s awesome”; “Speechless”; or “Why?”

On to Beaumont Hamel. A rare preserved battlefield of the Somme. We wander through the zig-zagging trenches of the British front line. From them, in July 1916, British and Canadian troops went over the top. At walking pace, as ordered. In open country. Straight into the German machine-gun fire. After half an hour 1,800 men lay dead and 3,000 wounded. Casualty rate: 90 per cent.

Trenches untouched since - except by nature. Now grass-covered, they harbour frogs, butterflies, mushrooms, cow parsley and thistles. Different from the rats, the lice and the ever-present mud endured by that generation of doomed youth.

“Remember, you’re walking on those whose bodies were never found,” Nick Burkitt warns the students. With due restraint, they spread out across No Man’s Land, still marked by shell craters. Time for some field work on military tactics. The task: to discover why this attack was such a disaster. They measure the distance to the German front line. It’s a mere 200 yards. They stop at the “Tree of Death”, the only tree here to survive the war. They note the Germans’ trump cards: their higher position, their deeper bunkers, the ravine behind their line. “Good place to stash their gear,” one girl observes.

On the road again. Near Arras, personal memories stir. Here, my father came into the front line. Aged 17, only a couple of years older than the Chesham students. One of hundreds of under-age volunteers bursting to have a crack at the Kaiser. I imagine how he felt, surrounded by death. Invalided out with trench fever, my father never spoke of what he had seen here.

On to Vimy Ridge. The scene of a celebrated victory by Canadian troops. Trenches, reinforced with concrete mock-sandbags and duck boards, are less evocative here. I am amazed by a trip through underground passages, used for sleeping quarters and administration. A reminder of that other, often forgotten hazard of war: tunnelling under the enemy trenches.

Back towards Belgium, we pass rebuilt villages, small cemeteries set in corn and cabbage fields. The students are thoughtful. “I didn’t realise how many people had to be sacrificed,” Peter says. Fiona adds: “It’s different when you stand in a trench, you can really picture what was going on.”

Friday: To the Ypres salient. The town itself was flattened in the conflict, but beautifully restored afterwards. We wander round the large Cloth Hall museum. Vivid photographs of trench life, but also troops relaxing behind the lines. A plethora of touchingly domestic relics: mugs, water bottles, and sewing kits.

On to Sanctuary Wood. More shell holes and trenches, this time realistically muddy. The students venture through them. “I must be the only Year 10 who’s getting trench foot,” Kelly says. Later they’re chastened by graphic pictures of corpses in the museum. A lively debate: should such photos be taken at all?

Next stop Tynecot, the largest Commonwealth war cemetery in the world. Gentle farmland below the slopes of Passchendaele. After 13 weeks of fighting, the village was taken by the allies. Cost: 300,000 British and 260,000 German casualties.

On the back wall, the names of 35,000 British killed in the salient who were never buried. The students do some evidence gathering among the 12,000 graves. Many accepting epitaphs (“Greater love has no man”, and so on), but also some dissenting: “Thy will Lord, not mine”. Four graves are a surprise: they’re German, commemorating some last-ditch gallantry.

The Langemark cemetery a few miles on is also German. Dark, wooded, sombre. Black stones on the ground, each covering six or eight or 20 dead at a time. Many commemorate “ein unbekannter Deutsches soldat”. In the centre a shock: a mass grave, holding the remains of 25,000 German soldiers.

The students’ task is to compare the impact of the two cemeteries. One girl does so forcefully: “I think it’s unfair, the ordinary soldiers on both sides didn’t want the war, but when we kill the Germans they get crappy little graves.”

Evening, and it’s back to the Menin Gate at Ypres. We listen with the crowds to two buglers playing the Last Post. This moving ceremony has been carried out every night since 1929. Around us in the dusk, yet more thousands of names etched into the vast stone arch: the men of the allied armies who defended Ypres, but who have no known grave.

The day has had its effect on the students. “You realise that war is not numbers, but people,” says Edward. “The Germans are the same as us, we’re all human.” Joy makes a particular link: “I thought it was just something that happened in the past, but now I realise what people have done for us.”

Later in the bar, an informal post-mortem with the teachers. They are satisfied with the outcome. Videos, photos, primary documents about the war can only do so much, Neil DeMarco suggests. “Coming to the battlefields allows the students to make what they will of it themselves.”

Jonathan Croall and Chesham High School travelled by arrangement with NST, Chiltern House, Bristol Avenue, Blackpool FY2 0FA. Tel: 01253 352525. Tours are tailor-made to suit schools’ requirements.

The Commonwealth War Graves Commission has produced Memorial and Memory, a video with teachers’ notes for use during tours of the battlefields (Pounds 4.75). Details: 01628 34221