The head of Donaldson's College in Edinburgh says that some deaf pupils are being short-changed because teachers have only a basic grasp of British Sign Language.
Janet Allan, principal of the national special school for deaf children, argues in the General Assembly education report that it would be unimaginable that hearing children were taught by teachers with a low level of Standard grade English or who were struggling to put over concepts because of their restricted vocabulary.
"This is no less true for the deaf child. It is therefore unacceptable that a deaf child be educated by people who have only a very basic knowledge of British Sign Language. In many, but certainly not all, units across Scotland, the most fluent British Sign Language users have BSL1, which is approximately the level of Foundation at Standard grade," Mrs Allan writes.
She estimates that around 2,445 children and young people in Scotland are severely or profoundly deaf and that 45 per cent of deaf children have additional difficulties. Yet the preferred Scottish Executive policy is mainstreaming.
Mrs Allan points to continuing difficulties with this, even where there are well qualified language support assistants. "The problem is equally difficult in the deaf child's access to other members of the school staff like school secretaries, lunch ladies and janitors who have an important part to play," she says.
"Where well qualified language support assistants are provided there remain two difficulties: one is that the assistant requires to have breaks for coffee and lunch and is frequently not with the child when the child is socialising with his or her peers.
"This leaves the deaf child potentially very isolated. If a circumstance does prevail where the assistant is available at these times, the interaction between the deaf child and the hearing children is fundamentally altered by the presence of an adult. The deaf child in the mainstream setting is frequently dependent on the services of one person."
A further concern is where the assistant fails to grasp the concepts being explained by the teacher and cannot translate effectively for the child.
"This is especially so for the academically able child who may be taking Highers in subjects that the language assistant has never studied," Mrs Allan says.