Show-and-tell lessons often unearth strange objects with interesting back stories.
But one school in south Wales got more than it bargained for recently when one girl brought in a Second World War shell as part of a project to commemorate the 65th anniversary of D-Day.
Worried that the shell might explode, the school immediately contacted the police, who arranged for a bomb disposal team to attend the area. They performed a controlled explosion on Aberavon Beach, which could be heard across the town.
One local said: "I don't know if it was a bomb or what but I know it made a massive noise when they blew it up."