Girls are misbehaving more in the classroom now than they were five years ago, a survey of teachers suggests.
A fifth of teachers believe girls' behaviour is now more difficult than boys, according to a poll by the Association of Teachers and Lecturers (ATL).
Almost half (48%) said they think the behaviour of female pupils has worsened over the last five years, with a similar proportion (44%) saying it has got worse in two years. In comparison, 43% said boys' behaviour has deteriorated in two years.
The poll, which questioned over 800 school staff, found that while boys are more likely to be disrespectful and verbally and physically aggressive, girls are more likely to be bullies.
Four times as many teachers said they had witnessed girls bullying than boys (44% to 10%), spreading rumours, making snide comments or leaving a fellow pupil out.
One 34-year-old teacher from Reading told researchers: "Girls spread rumours and fall-outs last a long time. Boys tend to sort it out fairly quickly."
A Bedfordshire primary school teacher said: "Boys are generally more physical and their behaviour is more noticeable. Girls are often sneakier about misbehaving, they often say nasty things which end up disrupting the lesson just as much as the boys, as other children get upset and can't focus on their work. They are usually the ones who refuse to comply with instructions."
Some 6% of those questioned said they had seen girls pushing, spitting, kicking, punching or hitting, compared to 40% who had seen this behaviour in boys.
At ATL's annual conference in Liverpool next week, the union will debate a motion expressing concern that an increasing number of girls are being excluded from secondary school. The motion calls on ATL's executive to investigate the problem and to urge ministers to help develop programmes to assist pupils, schools and staff.
The poll found that, overall, more than half (56%) of those questioned think pupil behaviour has worsened over the last five years and 45% said it has got worse in the last two.