Explanation of Context: Rosalita's classmates were laughing at her because she almost fell in the hallway. Mocking laugh represents a mean laugh, where the people make fun of somebody because of something, as Rosalita's classmates were making fun of her because she stumbled.
As we can see in the picture where the student is mocking his professor behind his back by his mean laugh and grimaces which he uses to make fun of his professor.
