An eight-year-old boy from Essex was left behind on a school trip after the coach departed without him.
Jack Hewett, of Laindon Park Primary, Basildon, had been out with classmates at Grangewaters Outdoor Education Centre in South Ockendon.
He told staff at the centre, who informed his school, and the coach returned 15 minutes later.
The school apologised to his mother and has reviewed its outdoor trip policy, which will now include a head count.
The acting headteacher also met with Jack's mother and apologised for the mistake.
A statement added: "When the children were boarding the coach to come home, a child was left behind.
"The child quickly made himself known to staff at Grangewaters and they informed the school, within 15 minutes the coach had returned and picked up the missing child."