The study said that some "excellent" education was being provided in schools north of the border.

Inspectors were also impressed by the commitment shown by school staff and their provision of high-quality care in welcoming environments.

But the report identified a need to improve the curriculum in 55% the 65 schools which were inspected between 1998 and 2002.

The overall picture is mixed with the report identifying some significant areas where improvements are required if all pupils are to achieve their fullest potential Graham Donaldson Senior chief inspector

And it called for an extension of the school week to match the hours which are usual in mainstream education.

The standards and quality report is the first of its kind to be published by HM Inspectorate of Education (HMIE) on the sector.

Senior chief inspector Graham Donaldson said: "I am pleased that we are able to highlight many positive aspects in Scotland's special schools.

"At its best, the quality of education in our special schools is excellent.

"However, the overall picture is mixed with the report identifying some significant areas where improvements are required if all pupils are to achieve their fullest potential."

Restricted choice

The report said that the majority of special schools need to ensure their pupils receive a broad and balanced curriculum, especially at secondary level.

Weaknesses in curriculum structures were identified in 55% of the schools inspected.

Senior pupils in a number of schools were offered a restricted choice of subjects which did not adequately prepare them for adult life.

Strengths in special schools included ethos, personal and social development and the high quality of pastoral care HMIE spokesperson

Almost all special schools operate a shorter week than mainstream schools.

The inspectors said this should be extended, a move which would increase the time and opportunities available for teaching.

They also called on teachers to set sufficiently challenging targets and tasks for pupils.

The report was based on visits to 30% of Scotland's special schools, the majority of which are publicly funded.

It said they played an important role in educating pupils with learning difficulties or who exhibit challenging behaviour.

Self-esteem

Inspectors were particularly impressed by the commitment of staff.

"Strengths in special schools included ethos, personal and social development and the high quality of pastoral care," said an HMIE spokesperson.

"All which help pupils develop self-esteem and independence."

Children often have lengthy travelling time to school which... might make a full-length school day a counter-productive aim Cosla spokesman

The Scottish Executive welcomed the report.

"The recommendations should enable education authorities and governing bodies to follow a relevant agenda for improvement," said a spokesperson.

"The executive is committed to improving the learning experience of pupils in special schools.

"Only last week we published our Additional Support for Learning Bill and our learning support framework document, which include a number of proposals to achieve this."

Learning needs

In addition, a requirement to extend the length of the school day comes into effect in August.

However, a spokesman for the Convention of Scottish Local Authorities said such a move was not as straightforward as it would seem.

"Children often have lengthy travelling time to school which, depending on their individual needs, might make a full-length school day a counter-productive aim," he said.

"It also depends on the individual learning needs of the child as to whether or not a full day's schooling is in their best interests."

Social development

He added that the areas of weakness identified in the report would be "considered seriously".

Kate Higgins of Capability Scotland also welcomed the report and said it was no surprise that schools fared well when it came to pastoral care and social development.

She said that meeting these needs was as important as meeting educational needs.

"Capability Scotland would hope that on the back of this report the Scottish Executive will now put in place a national educational strategy for children who require learning support," she added.