The findings suggest that assistants are undervalued and that the job has evolved from one of "domestic helper" to "assistant teacher" - beyond the original remit that assistants should "free teachers' time to teach".
According to one report, assistants doing less demanding jobs should be equated with NHS healthcare assistants (who earn pound;11,879-pound;14,739). Those carrying out more demanding roles should be paid a similar salary to that of a departmental secretary in the NHS or a maintenance craft worker (Pounds 13,694-pound;16,389).
Currently, classroom assistants' salaries vary depending on local authority pay scales. They are paid on the lowest clerical grade - pound;10,000 to Pounds 13,500 a year - but in reality earn much less (around pound;5,500-Pounds 8,500) because they work only 27.5 hours a week during term time.
The findings could have major implications for local government finances - already under pressure from a number of equal pay for equal status claims.
The reports' authors also state that a small but significant number of classroom assistants are performing duties which cross the boundaries of what are considered qualified teachers' duties. This may generate pressure in Scotland to follow the English model of higher learning teaching assistants, who earn around pound;20,000 and are allowed to be independent operators and undertake a range of teaching and learning functions. To date, the Scottish teaching unions have vigorously defended the teacher's monopoly of teaching and learning functions in the classroom.
John Stodter, general secretary of the Association of Directors of Education in Scotland, said the issue of equal pay for classroom assistants was being addressed by the job evaluations being done in every local authority under the equal pay regulations.
However, Mr Stodter warned that this did not mean that classroom assistants everywhere would be paid the same. Authorities were under a duty simply to make salaries consistent within their own authority and did not have to compare them with salaries elsewhere.
He believed that authorities would have to tackle the strategic issue of career progression for classroom assistants. "We (the ADES) have had talks with headteachers from England about the idea of people who are not teachers taking whole classes," Mr Stodter said. "I can't see that in Scotland, but there has to be less demarcation."
The reports, commissioned by independent experts for the EOC's investigation, found a considerable variation in the duties being performed by assistants, with some at the top of the range using relatively advanced ICT scales, modern language skills, and teaching and learning skills with children with additional needs.
One found: "A small but significant group of classroom assistants appear to be working beyond the policy remit, being involved in higher level learning activities, for example planning the curriculum.
Developing the school curriculum is, according to annex B of the teachers'
agreement, the duty of qualified teachers."
The report quotes one director of education who said: "The kind of involvement that might include sitting with a child and helping them with a task prescribed by the teacher or hearing their reading, these are things where I would submit that there's a potential for overlap (with teaching), but if you're alert to it you manage it."
A headteacher said: "I would certainly put them up with a nursery nurse because they do the planning with the teacher, they do the assessment even if it is a minor part and they certainly have an understanding of the learning process."
In a comparison with the situation south of the border, the report states:
"Higher level teaching assistants . . . carry out a range of tasks traditionally associated with teaching, including teaching classes under supervision." It notes, however, that the Scottish Executive and directors of education believe that this model is likely to be heavily resisted here.
Another of the studies, by the Scottish Centre for Employment Research, finds that "in the shift from policy to practice the job has evolved and expanded, with changes to the work and employment but not status and pay".
Since assistants were introduced in 1998, no mechanism has been introduced by councils to assess and rate the skills and competencies of classroom assistants.
It then warns: "The failure to update the existing grading and move towards single status suggests that local authorities might be underpaying classroom assistants and also neglecting to establish equal pay for work of equal value for a group that is predominantly female."
The report by a team of experts specialising in job evaluation concluded that there were broadly three groups of classroom assistant with more or less demanding functions. They found that all were paid less than comparably demanding roles in the health service. For the more demanding classroom assistant roles, the difference was "significant".
The team's recommendations include that local authorities carry out their own evaluations of classroom assistant roles; that they create a job description questionnaire to get a better understanding of what classroom assistants do; and that they set up a career grade system allowing classroom assistants to progress from the less demanding roles to more demanding ones.
A spokeswoman for the Scottish Executive said: "The implementation guidance makes it perfectly clear that the role of classroom assistants is to support teachers. They perform a valuable function by relieving teachers of non-teaching duties but they are not there to teach."