Women teachers are holding back boy students by blaming them for typically male behavior, according to a new study. Women teachers are always saying that boys are "silly" in class. They refuse to "sit nicely like girls" and are more likely to be addicted to "schoolboy tricks".Women teachers may also keep low expectations of boys' academic achievement and encourage girls to work harder by letting them think they are cleverer than boys. The study suggests that under-performance among boys in most national exams could be linked to lower expectations of their women teachers. The researchers did their research mainly on women teachers, since nearly 90 percent of primary school teachers are female. According to the research, women teachers said they often found boys' play in the classroom or in the playground, such as playing with toy guns. The researcher also found that boys were often punished and urged to follow a more feminine style of play instead of being taught how to play responsibly with their favorite toys by their women teachers. Bonny Hartley, the study's lead author, said, "By seven or eight years old, children of both boys and girls believe that boys are less focused, less able, and less successful than girls -- and think that adults admit this idea. There are signs that these expectations have the potential to become self-fulfilling in influencing children's achievement. Boys are really held back by their women teachers." The reason why boys perform worse in most national exams than girls is that    _           .
girls are cleverer than boys in primary schools. boys enjoy playing with toy guns in school. boys are more careless when taking exams. women teachers keep lower expectations of boys.