"attended a catholic school" - Experiences that define you as a person

I attended a catholic school for five years in elementary and i transferred to a public school when i was in grade six.This happening had truly opened my eyes to see the real world. i was raised in a good school having kind classmates and teachers and so i live a happy life, until i get to know and experienced as a public student. The difference between the students, teachers, and the environment were really big. It was also that time that my family experienced a big problem. This situation had made a great part in shaping my personality. I was able to differentiate and get part of this two worlds.Why is my teacher not teaching? Why does she sell those foods to students? How did my classmates learned to speak in rude way to everyone whether its an adult or not? Are we really studying? this was a shock at first but i finally adapt that environment. this happening didn't weaken my dreams to help people who needed me , instead this strengthen my dreams.

>this is my third paragraph in my essay:)
I know i have lots of errors so please help me identify my mistakes in punctuation and grammar.
Thanks in advance !!!

Look at tenses first. This is fundamental !

I attended a catholic school for five years in elementary and i transferred to a public school when i was in grade six.
-> I attended a catholic school for five years in elementary. Then, I transferred to a public school when I was in six grade.

How did my classmates learned to speak in rude way to everyone whether its an adult or not?
-> How did my classmates learn to speak in rude way to everyone whether it` s an adult or not?

I think there are more errors like capital letter or other things.

@sunglyeol i know some capitalization of my words are wrong like "i", and thank you !!

whats correct?
" I was able to differentiate and get part of (this / these) two worlds."

@Poonie Cha , i don't know what's Fundamental. Please tell me whats wrong with my work. :))