Answers your questions
Like many secondary schools we have a yawning gap between the achievement of boys and girls in GCSE, indeed at every stage. I have heard that separate-sex teaching can dramatically improve the performance of boys. Should we persuade our school to adopt this idea? Or is it none of our business? (Teachers have implied this.) This is an issue on which it is difficult - and perhaps unhelpful - to draw territorial boundaries.
Governors are charged with raising standards, and the problem of boys is one of the main obstacles to improvement in many schools. Such necessary changes are a strategic issue which governors should be concerned with. However, the professional input into such a decision has to be vast - not only any wisdom available from national experience but also the teachers' judgment about the relevant local circumstances.
In areas where basic industry has disappeared and jobs for male school-leavers are few, you have an easy explanation for an anti-achivement attitude, but affluence might also have a bearing.
Any school with this problem needs to engage staff, governors and perhaps also parents and local employers in a dialogue where territorial arguments about "whose job it is" are set aside. There needs to be an analysis of contributory factors. Curriculum options and the range of out-of-school activities are central. Attendance is an obvious one: if you look at the group in which attendance in Year 11 falls off to a point where some have unofficially left at Easter, what is the gender distribution?
Schools may have success with simpler tactics such as fiercer absence-chasing among the vulnerable, short-term targets for boys, tighter schedules for course-work, experimenting with the scale and character of Easter revision classes and the tactics of behaviour management. I'm not ruling out experiments with single-sex teaching, but don't make any big experiment a wholesale one until you are sure it is right for your school.