My grandmother was in the Luftwaffe.” James offered his observation from the back of the room, in response to my request that the class find out what their grandparents had done during the Second World War.

The inquiry had so far produced a few accounts of the Blitz, some anecdotes from the Eighth Army, a recipe for “melted moments”, and a best kept secret, that one child was the descendant of an evacuee. But none of this compared with James’s startling revelation.

A few giggles broke the confused silence, but inside me, the voice of experience urged caution. “How could that be, James?” I asked gently. James then slowly teased out a fascinating and complex explanation. Later I checked, and it was true that in the confusion of post-war Europe - with its occupying forces, refugees, and prisoners of war - fraternisation between recent enemies had been easy, natural and inevitable. Human love recognises no boundaries.

And so it was love and geo-graphy together that had placed James, with his Luftwaffe grandmother, in my classroom in rural Wiltshire.

I had been studying “Britain since 1930”, assuming that the class was one nation, all on the same side as it were, and I had been wrong. I had never made the assumption explicit, but it had definitely been there. James’s revelation changed my teaching of this particular topic for ever, but it would not be the last time that I would be knocked off balance in this way.

A little while ago, the whole school was involved in the same project which was treated as the Second World War “topped and tailed”. We did all the usual things. We examined evidence (newspapers, books, film, artefacts), we dressed up the biggest children (still too small) in battledress. We interrogated the cleaner, we cooked, we acted, we wrote, drew and painted. And in the end we had a “happening” instead of the usual school Open Day. Parents came to sample our Second World War experience, and they came in droves.

One classroom was given over to cooking contemporary recipes, another to “make and mend”. A sing-song took place in another room. The library was turned into a Lyons Corner House, where tea and cake were served all afternoon. In the hall, a GI dance took place with children encouraging parents to get “in the mood” and dance. It was the culmination of many weeks of study and it was great fun.

It was fun, too, when the Year 6 teacher embarked on the same topic recently. My involvement this time was at arm’s length, but I was soon drawn unexpectedly into the project when the teacher sent the children home on a familiar mission to find out what their grandparents and great-grandparents had done during the war. On Monday there was a knock on my door. It was Mrs Greenman. “Could I have a word?” She wanted to explain why Joanna might be upset.

Joanna had gone home and asked the question and, conscientious, intelligent and perceptive, she would not be fobbed off with an incomplete or dismissive answer. A family conference had to be held, telephone calls had to be made and, in the end, a decision taken. It was time for the truth.

On Sunday morning Joanna was allowed to talk to granddad on the telephone. He was frail and his English, after all these years, was still shaky, but the message was strong. During the war he had been sent to a concentration camp in Poland. He had survived, but 12 members of his family had not. The loss was his loss and it was Joanna’s, and she was old enough to understand this. So on that Sunday Joanna had cried for her lost relatives, for the great-aunts and great-uncles she had never known and would never know.

I met her in the corridor on Monday morning. She knew that I knew, and although she smiled at me, her eyes immediately filled with tears.

Teaching history can be fun, but history itself is not to be taken lightly. After all, history is about seeking after truth, and the truth can often be painful. For me, the truth about the Second World War will always lie, not in the fun happenings on a School Open Day, but in the tears of a little girl.

Paul Noble is head of St Andrew’sprimary school, Blunsdon, Wiltshire.