Break the Haughty: While she is technically right when she tells Ximena that Marcelina was cheating on a test, the kids (already not too thrilled with her arrogance) subject her to this via totally shunning her. The until then proud Maria Joaquina was soon reduced to a sobbing wreck.
Dumb Blonde: Averted, since he is an excellent student.
Informed Judaism: His Jewish faith is mentioned sometimes (like when he and Valeria wonder if it'll be a hindrance in their married life since Valeria is raised Catholic, or when he's in a synagogue), but doesn't play a huge role in his life as a whole.
The Determinator - Plucky Girl: Unlike all other students whose families were poor (Mario, Cirilo, Jaime), Carmen did very well in school. In fact, she did much better than various other students whose families were better off (such as Pablo and Laura).
Perpetual Poverty: At first, due to her parents being separated. She needed new shoes, and later a full white outfit (complete with gloves)- which La Patrulla Salvadora procure for her!. It Gets Better, though, when her parents reconciled.
Tomboyish Ponytail: Subverted, since as ladylike and tender as she was, she also was a good student who wanted to learn how to swim.
Abusive Parents: His father is an okay person if often away due to his hard work. His mother is dead, and his stepmother hates him since she doesn't consider him her child.
Romantic False Lead: At first, it seems like she will steal David away from Valeria. But Margarita ends up losing interest in David, he and Valeria get back together, and Margarita moves on and stays friends with Valeria.