When I was 5 my parents put me in a "normal" kindergarten, where I failed to do literally anything - I wouldn't make any marks on any of the sheets, not even my name. They were worried I had some kind of developmental problem.

Somewhat out of desperation they put me in a Montessori school. By the end of Kindergarten I was reading at a 3rd grade level and understood the basics of multiplication.

We ended up moving by 1st grade and I went back to "normal school", where I did ok since I already knew everything.