Half of state-funded schools in England for children with special educational needs and disabilities are oversubscribed, BBC research has found.
Schools have converted portable cabins and even cupboards into teaching spaces because of a lack of room. Head teachers say this puts pressure on staff and makes pupils anxious.
Parents say the wait for places means their children are missing education.
The Department for Education says it is spending £2.6bn on new places.
Over the past five years, the number of children and young people being educated in specialist schools and colleges in England has increased by nearly a third - to 142,028 last year.
