Some pupils have fled war-torn Sierra Leone, while others are sent from families in Nigeria or Jamaica to stay in London with relatives they hardly know.
But Mark Parsons, headteacher, says all pupils who arrive mid-year at Oliver Goldsmith primary in Camberwell, London, need extra attention. "I've had kids who have hidden in a hole for three months, a girl who lived in the jungle for six months, and a mum who wanted to show me her scars from a machete attack," he said.
"We are brilliant at settling children, but when a new child comes they need more support and it changes the dynamic of a class - teachers find it very, very hard."
For five years, an average of 120 pupils a year joined the 600-strong school mid-year - including 11-year-old Damilola Taylor, who was murdered in 2000.
This year numbers fell to around 96, but Mr Parsons said extra funding could transform their experience.
He said: "It really does need serious funding to have much smaller classes so more support workers can bring the pupils on faster and tackle their bad behaviour."