How frustrating is it when you misplace your mobile? Or cannot find your keys anywhere?
A Monmouthshire school has lost something equally important - and has only a week to find it before the 59-year-old building is flattened.
A time capsule made by past pupils is buried in Caldicot Comprehensive's 50 acre site - but no-one recorded where.
Staff and pupils are desperately digging the site before the school moves to its new £31m home.
"We have a few different dates about when it was supposedly buried," said deputy head of history Matt Handford.
"Some have said it was when the school opened in 1958 and others said it could have been on its 25th anniversary in 1983."
The school's history club, led by Mr Handford, has been undertaking "living history" archaeological digs over the last few months to try to locate the missing capsule.
The search has been narrowed down to around the school's Greyhill building, which was officially opened by the Duke of Edinburgh.
It is thought former history teacher Margaret Crimmins and her class buried the time capsule around the school's silver jubilee in 1983.
The school has tried to track down Ms Crimmins, who was last known to be teaching in the Bristol area, but with no luck.
"If any past pupil or teacher was part of the burial back then, we'd love for them to get in in touch," appealed Mr Handford.
"The time capsule is important because it is part of the school's history.
"We have been using a metal detector and digging trenches, so using it to teach pupils how to conduct an archaeological dig and how you record finds.
"It's a little bit of living history and we'd love to find it because current pupils could really relate to how their fellow students used to learn and live."
But time is running out as staff have been told they must vacate the current site by Friday.
"The old school will be demolished in due course," added Caldicot deputy head Mark Sexton.
"If we can't find the time capsule ourselves, we'll ask the contractors nicely if they'd be kind enough to help us.
"It is a really important project for the school. We will do a current 2017 time capsule for the new school - and before you ask, no it won't be buried!"