Almost half of looked-after children have had to make one additional change of school since coming into care, according to a report.
One in five looked-after children in the UK had experienced two or more changes of school, in addition to expected age-related moves, the Fostering Network survey found.
And the education of one in 20 children in care had been disrupted by at least four extra school changes.
Network chief executive Robert Tapsfield said: “Children coming into care have a hard enough time finding their feet without having to cope with a school move.
“And for those who get moved time and time again, it’s hardly surprising that they fail to match the achievements of children from more stable backgrounds.”
He said more foster carers were needed so children could be cared for in their local area. There is an estimated UK shortfall of 10,000 foster carers.
The survey was released to coincide with this year’s Foster Care Fortnight, which runs from 8 to 21 May.