Human brain differs from every individual, not the size and the weight but the content. Cognitive thinking develops with experiences and application of those experiences. Every person is a sum of what happens in one’s lifetime.

Our schooling system is one of the most dysfunctional set-ups you could come across. Mostly the decision makers in schooling system are useless academicians assisting the clueless politicians.
Akira Kurosawa, great Japanese director in his autobiography touches a little bit on this and he goes on to say,
Intelligence develops at differing rates. It’s a mistake to decree that a year’s progress must take place within exactly one year, no more no less.
It’s a fascinating concept to think about. Our school systems have yearly curriculum and we are deemed a failure if we don’t pass that year’s syllabus in the same year. I have personally know some friends who did very badly at school, barely passed and kept their heads above water gone on to achieve some amazing success.
If you have kids at home or brothers / sisters / niece / nephews studying, it is important for you to understand that the rate of growth of intelligence differs from child to child and don’t send them to every tuition possibly can to load them with more mental stress. That’s only going to make the growth slower. And painful. For them and for you.
Stay curious!