It's a common problem but it costs schools a lot of money to keep chasing unreturned books or replacing them.
Prizes
Radio Five's asked schools to get kids to hunt out lost books and 10 random schools will win a prize.
It seems to be working: at Northgate Junior School, Guisborough, books left by a pupil who left three years ago came back with his brother!
And at Greenfield School Community & Arts College, Newton Aycliffe, a book came back from a hotel in Poland where a pupil had been!