A Gloucestershire school has become the first to take part in a survey of 20th-century military sites.
The Defence of Britain project is a five-year scheme launched last year to survey every pillbox, bunker, radar site, store, prisoner-of-war camp, anti-aircraft battery, fuel dump and hospital.
The organisers, backed by the Department of National Heritage and the Imperial War Museum, are compiling a Domesday Book of defence while the people involved with the structures are still living.
They hope hundreds of schools will follow Beaudesert Park School, a preparatory school near Stroud.
At Beaudesert Park, 13-year-olds surveyed a decoy building designed to lure German aircraft to drop bombs on empty countryside.
Archaeologist Dr Alan Peacey, a part-time teacher, said: "It was not at all difficult to interest them, which was a bit of a surprise. The survey brings home to them how seriously under threat we were in the last war. It also brings a greater understanding of current affairs and the news."
John Hellis, project archaeologist, said: "A few may say this is glorifying war, but the majority will see it as part of our history. This was the first and hopefully the last war in which everyone was involved, everybody was in the firing line."