girls are always girls means that they are emotional when their judgment is based on emotion not logic. i mean this by that
no i get you with no doubt when i say that this is a rule of creation it means that always most people act look like they suppose to act i mean physical react
you know what am i mean
you say it depends on student capacity to teach them a lesson
here it is :
"
but the teacher didn't teach it! why? no one knows 
but i know!
because of some reasons related to the capacity of students" your sentence
maybe the problem is belong to the teacher and the teacher had not enough capacity to teach them
beside i don,t blame you
what do you got from my sentence