Primary school 4th year (as it was called then). Teacher had some items/words and asked what they had in common (can't remember the exact phrasing), anyway it was things like triangle, tricycle, triceratops. I usually kept quiet even if I knew the answer, but this time nobody spoke up and I was feeling unusually confident. "Tri", I said. The teacher wrote "try" on the board and basically humiliated me. "Anyone else?" I think there was one other answer, and then somebody else said "tri" (or maybe they were clearer and said "they all start with tri"). Anyway, they got congratulated and my protests that that was what I said went completely unheard.

I mean, if you know the answer is "tri", why would you hear and write "try". This incident probably knocked my confidence and made me even more shy of sticking my hand up than I already was.