Miss O'Brien was a 50ish year old, Irish immigrant, traditional, Catholic nun. She taught at Catholic grade schools for most of her adult life. When I met her, it was her second of what turned out to be three years teaching in public school in St. Louis.
Sister Mary Margaret had been given "leave" by her convent to come home to St. Louis and care for her elderly, dying mother. To pay the bills, she taught school. Granted, it was a public school, but that didn't really matter to her.
When we arrived in the morning, there she was in a black dress, white smock, black hose, black shoes, and a very large rosary looped in the belt on her dress. She wore the exact, same thing, every day.
She brooked absolutely zero nonsense. No need for a ruler to the hand, Sister could silence the rowdiest child with a glare. I once saw her break up a fight between several, large, 8th graders by simply walking into the melee and shouting, "On your knees and beg God for mercy for your evil fighting!" And they did.
We were always the last class to reach the lunchroom, as at noon, she knelt and prayed the Angelus. Catholic children were expected to join her at their desks and we Protestants and the lone Jewish child sat with our hands folded in respectful silence.
Regarding the Jewish boy, one of the Catholic boys once decided to shove him and call him some bad name. I'm not sure how a large woman like Miss O'Brien could move so fast, but she was on him in half a heartbeat. Hoisting her Catholic co-religionist in the air, she spoke directly to him, "Shame. Shame! Did not your parents teach that our blessed Lord and his mother were Jews? Apologize and I expect you in confession on Saturday, so Father can deal with this."
So many other stories I could tell about the good sister. There was the time she led us through the smoke filled hallways when there was a fire in the school. Or the children who shared her simple lunch, because they had nothing to eat.
Sister Mary Margaret O'Brien, I pray that God grants you rest and joy in the eternal kingdom, through Christ our Lord. Amen.