The findings come as ministers step up their campaign to hit primary school targets in maths and English.
This month they will start their biggest ever push to get parents involved in education. Next week sees Family Learning Day to be followed by the launch of the National Year of Reading.
This encompasses a television advertising campaign, literacy storylines in soap operas and a "Read Me" logo on everything from crisp packets to billboards.
Women from poorer families understand the importance of a good education for their children. However, they have little confidence in their own ability to help their children learn and feel too intimidated by schools and teachers to ask for help, said the Campaign for Learning, a charity jointly funded by the Department for Education and Employment and British industry.
"You need a string of words behind your name just to work in a shop," said one respondent. "It's a bit embarrassing when they come home and say: 'Oh, how do you spell this or how do you do maths?' and you haven't got a clue," said another.
* Making the most of the Year of Reading, centre pages