Just half the parents of state school pupils find it easy to obtain information about how their child is progressing in the classroom, a new survey reveals.
Parents also complain that school reports are too often bland, generalised and littered with jargon.
The study on parental involvement, carried out by the Scottish Parliament, suggests that private schools are better at communicating with families than their counterparts in the state sector.
Some 88 per cent of the independent school parents questioned agreed it was easy to get information about their child's academic progress. By contrast, only 53 per cent of state-school parents agreed, and 25 per cent disagreed.
"I receive more information on my car testing through an MOT than my child through S1-S3," one parent told the researchers.
In addition, 88 per cent of parents with children in the independent sector said the information they received from the school was helpful, compared with 56 per cent in state schools.
"I think teachers and reports use too much Curriculum for Excellence language that is not always helpful to parents," one respondent said.
Eileen Prior, executive director of the Scottish Parent Teacher Council (SPTC), said that in state schools parents were often seen as "difficult".
"Our view is that parental involvement continues to be seen as peripheral, not central, to the effectiveness of a school and the desire to close the attainment gap," she added. "In fact, the tenor of the dialogue in schools around parents is often negative, with parents portrayed as difficult and there to be managed or controlled. Indeed, they are often portrayed as part of the problem around children's attainment, rather than part of the solution."
Ms Prior called for teachers and school leaders to be better educated about parental involvement and for proven interventions to be implemented consistently. The SPTC would also support Scotland-specific research looking at the impact of parental involvement on attainment, she said.
The survey of just over 2,600 parents was carried out to help inform the education committee's year-long focus on attainment. Parental involvement is considered key in improving pupils' attainment; international research has shown that family is as influential in educational outcomes as high-quality teaching and effective schools.
The report reveals that many parents feel that better use could be made of technology to keep them informed, and that more account needs to be taken of working hours.
According to Iain Ellis, chair of the National Parent Forum of Scotland, parental involvement is "spectacular" in some schools but "non-existent" in others.
"The problem is it varies across the country from a huge amount to virtually no parental involvement at all, except what the school does because it has to," he said.
Independent schools, on the other hand, had high expectations of the role parents would play in their child's education, said John Edward, director of the Scottish Council of Independent Schools. They entered into agreements with parents and children from the outset, spelling out everyone's responsibilities.
"The expectation is not that parents will simply send their child off wearing the school uniform every morning," he said.
Education and Culture Committee convener Stewart Maxwell said the survey "paints an important picture about the need for schools and parents to work closer together in order that children can achieve their very best at school".
He added: "The survey also reveals that those with children in independent schools find it easier to get information about how their child is progressing than those in state schools."
The committee will discuss the research and parental involvement at its meeting next Tuesday.