Raina suggesting to the class that they make Michelle a giant get-well banner for her for moral support when she hears she's getting surgery. The teacher approves and the whole class pitches in to decorate it.
What's more, some parts of the banner describe all of Michelle's redeeming qualities, showing that she has other facets beyond her former preoccupation of teasing Raina.
Raina befriending Michelle.
The ending revealing that despite growing close with Michelle, Jane still holds Raina in the highest regard as her best friend. How does Raina know this? Because Jane told her about moving, but nobody else. That's how close the two are.
