Typically female interests, like socializing with peers and being creative, are rewarded in the school environment. They are encouraged to collaborate and express themselves through words, art and music. Typical male interests, however, like roughhousing, running around and expressing themselves through movement and hyperactivity, are punished in schools. 
Additionally, more young girls like to read, while many young boys prefer to play sports. This means while girls are building verbal proficiency and comprehension skills, both useful in academia, boys are developing hand-eye coordination skills, teamwork, and athleticism, none of which are useful in the classrooms or exam halls.
Finally, the subject matter taught in schools now favours female student participation. In the past, students studied Macbeth, Julius Caesar and Coriolanus, plays with masculine protagonists engaging in battles and facing down adversity. Now, the curriculum favours plays like Romeo and Juliet and literature from the Bronte sisters, Jane Austin and George Eliot, which appeal more to female audiences.
This war on boys’ interests only leads to more male students resenting the classroom environment, which leads to more boys misbehaving in class and then results in more missed class time due to disciplinary proceedings. This vicious cycle leaves boys underperforming at all levels and failing to thrive in the classroom.
This systemic issue is reflected in studies of the attitudes of male students towards their schools and teachers. Even boys that perform well academically often hold more negative views of their school, their teachers and their female peers, than female students do.