To answer my own question:
My 7th grade home room teacher & gym teacher (whose name I have forgotten entirely on account of being middle-aged) was a Sunday school teacher in the Church of God in Christ, the biggest church here in Memphis. The summer before I entered his class, the state legislature passed a law allowing for a moment of silence at the beginning of the school day; he either misinterpreted this authority or ignored it, because he led us in a flat-out prayer, often referring to COGIC literature in so doing. I was a member of COGIC way back when, but I already had my doubts, and it bothered me; being only 12, I said nothing. Nor did anyone else. But I do recall that one of my classmates–the only white girl in the class, incidentally–was very uncomfortable about this, though she never dared object. Being named Rosenthal probably accounts both for her discomfiture and her reticence to express it.
ETA: Cliffy, we were in the same school system, it seems. May I ask what grades you were in when this happened? For me it only ever happened in 7th grade; the home room teachers of my later years did not even do the moment of silence, much less an organized prayer.