I had a similar experience sort of, except mine was more into middle school.
I had been getting a bit delayed, and had fallen behind a year, until they finally had the sense to ask me what the problem was, and it turned out I was was bored!
My parents wanted to try putting me in a 'regular' school, they did and actually I loved it at first. It was a bit hard also because I am and have always been very shy, and was placed with people who were unfamiliar, but I liked the challenge it presented, I was fascinated to discover a kind of 'relativity'. I worked hard for a year and rapidly caught up to where I was supposed to be, with my assistant and a private tutor, and then was advanced an extra year and still did well. The bad thing was when I made it to high school, I got bored again and became a bit rebellious, and ended up dropping out... but still, my experience gave me a thirst for knowledge, and apparently I had exceeded a lot of people's expectations at times (it didn't seem special to me but apparently I had impressed several teachers), I still continue studying and reading a lot of things in my own time.
