I remember a certain time they were showing Christmas movies in school and my parents had me opt out, either that or it was opt in. Either way, I was escorted out of the classroom and did approved non-denominational activity at that time.
There were times when I had to explain things about Islam. I don't know how prideful I was about it. My thought process is I would just tell them the truth about whatever I knew about Islam as objectively as possible without any spin, and of course that would lead them to the all true light of the deen.
One time there was something where we had to choose old-timey sort of names for a historical school re-enactment thing and I chose the totally old-timey name of Adam. When asked to explain why, I went into a thing about how Adam was the first man on the planet and the first prophet of God as accepted by even Jews, Christians, and Muslims, and I started talking more about the religious story of Adam from my Islamic education perspective before I was stopped by my teacher, and made to feel awkward.
Another time, in fucking high school mind you (not my proudest moment), I was asked about Islamic history by my world history teacher. I started talking about how Muhammad found the truth while meditating in a cave and shit, and how fucking awesome of a dude he was. I don't think that was exactly what she was looking for there.
I also had the biggest problem with shorts, because I was taught that men had to cover their knees, and even though this was inconvenient for some things, there must be some reason god wanted it, so yeah no shorts for me, lol. The whole time I didn't even think how inconvenient it must be for Muslim women, even those who don't cover their hair. Meh, I was a stupid kid back then.