One memory from fifth grade still lingers with me, and was the instigation for my not believing in God: a student told the teacher she couldn't sing the songs we were practicing for a Christmas program, because it was against her faith. The teacher very nastily told her she'd have to stand in the hall every day while the rest of us sang (I vaguely remember some sort of comment about Jehovah's Witnesses, but it was a long time ago and I can't remember what was said).
Stand. No chair, no going to the library or even to sit in the principal's office to do other work. For an hour every day for weeks.
This young girl cried, but she went calmly and stood outside the door while the other students carried on. I was so shocked -- even at that young age -- that I would not sing nor participate in the program. That got a black mark put against me for the rest of the year, but it felt right. We were taught the Golden Rule, but it seemed nobody really followed it.