With school about to resume I accompanied a close young relative for a visit/orientation. First time going to school and all that. I remember my first day way back when and it was sort of scary, so I was along for support.
At one point a cognitive test was given. I can’t remember the science behind it nor its formal name as I was not paying close attention.
I passed with flying colors!
I can now say without embarrassment “I graduated Kindergarten”.
The next round is on me. 
Perhaps everything you learned was learned there 
.
Taiwan (and Japan) kindergartens are three years. My wife started early simply because she was bored and no one to play with so she went for four years, a fact I never let her forget — that she couldn’t pass kindergarten the first time.
Somewhat related story:
Several years ago during marathon training season, my running club ran along with a group of middle-school girls in some sort of informal 5K race. I’m happy to report that I beat every single one of the girls! One of them was pretty fast, but I held off her challenge in the end.
Sounds to me like you passed the entrance exam? The k-SATs? 
I didn’t need Kindergarten academically; I could already read my older sister’s 2nd grade primer (Dick and Jane) when I started Kinder at age 4. What I needed was the maturity and social skills. I couldn’t button or zip a coat, or tie my shoes. I don’t remember having any friends before K.
Come to think of it, I don’t remember having any friends in K, either. Or 1st, 2nd, or 3rd grade. I wonder how many people thought I would grow up to be a serial killer.
I am not sure. I was just a visiting relative, and took it on a lark. I was bespitten (a word I just made up) by the director who had had red hair and blue eyes (Yes, I am a male and roll that way ). I got to look at their agenda and it seems they will get to explore the world/nature if not close-up but from many other sources. Great for them.
All I remember from my kindergarten class is taking a nap, so I am slightly biased.