The moment during the choir's performance when Mathieu turns to Morhange, who had previously been slouching against a pillar, apparently still in trouble for dropping ink on Mathieu's head. Mathieu gestures to him, and Morhange gets his solo.
Mathieu: In [his] eyes, I read many things. Pride, the joy of being forgiven, but most of all- and this was new for him- a kind of gratitude.
The paper planes scene. As Mathieu leaves the school, the children toss paper airplanes out the window at him with goodbye messages written on them and wave at him from the window.
This exchange:
Violette: You haven't got any children? Mathieu: No. Well, I have 60.
The look on Pépinot's face when the bus stops and Mathieu opens the door for him. The last two sentences of the movie:
Pépinot was right. Mathieu was fired on a Saturday.
As Mathieu leaves the school, the children toss paper airplanes out the window at him with goodbye messages written on them and wave at him from the window.