They are also being taught that women should be subservient to men and that wives are "deserving of pain and retribution" by their husbands.
Sarah McGough, of the University of Illinois, told the AERA conference that she had been staggered by the amount of gender discrimination she found in Christian schools. "And I didn't go looking for sexism," she said.
She had intended to study religious instruction in Christian schools in Urbana, Illinois, but had switched the focus of her research after discovering how girls were being treated.
"I just sat at the back of the class in a state of shock when I realised what was happening," said Ms McGough.
The schools justified their gender policy by quoting St Paul: "Let a woman learn in silence with all submission. And I do not permit a woman to teach or to have authority over a man, but to be in silence. For Adam was formed first, then Eve." (1 Timothy 2: 11-13) "These views about women's inferiority are adopted by girls and they don't seek positions of leadership in school," said Ms McGough. "I often heard boys tell girls to get water for them."
She said Christian schools' exemption from tackling sexism should be revoked.
"These schools should not be teaching that girls are inferior - that sort of practice should be checked and regulated."
She was also disturbed to find that girls were being given abstinence-only sex education and did not know how to avoid pregnancy or sexually-transmitted diseases.
But abstinence education is backed by the Bush administration, which has put almost $120 million (pound;68m) into such programmes. This policy is controversial but it is paying some dividends, according to researchers at Auburn university, Alabama. They told the conference that 13 to 18-year-olds who had received five hours of lessons from "abstinence instructors" were more likely to be against premarital sex.
More than 61 per cent of students who received the lessons said they "certainly will or probably will" abstain from sex until marriage, compared with 49 per cent of those outside the programme. The study involved 943 adolescents in three school districts of a southern US state.
The researchers recognise that abstinence-only education has many critics but they argue that the Bush camp's views can be justified. "Research suggests that there are social, psychological and health gains to be realised from waiting until one is developmentally ready before being sexually active," they conclude.
Matt Buck 31