[belorn]

A bit more reasonable expectation of teachers is that they should be able to motivate both boys and girls equally.

A lot of things were different when your grandfather were in school. Most teachers were male, and boys had better grades than girls. The teaching profession was high status profession, highly respected in communities, and well paid. The post world war 1 and 2 era put a lot of focus on practical skills with practical applications in both home and work. In addition the life path of men had very little free choice, in large part to male only military drafts.

From my own reading of education research and reports, making the teacher profession more gender equal and higher status would likely improve the situation for boys without putting higher expectations on the teachers themselves. Beyond that, the lack of male only military drafts means that both boys and girls have now equal freedom to choose what they want to do, and just as some women do not want to enter the work market so do now some men.