When I was about seven years old, my stepbrother would take me around to the neighbors and bet them that I could spell any word they asked me to spell. Fortunately, his friends weren’t scholars by any means, so I never got asked anything I couldn’t handle.
One of them asked me if I could spell “radioactivity”, which I obliged easily. I doubt any of them knew for certain that I was right, but I knew it and I was proud.
Despite my stepbrother using me as a side show, he was not particularly happy that I was so smart. He had trouble in school and somehow I got punished for it.