In literature, there are five methods of characterization: physical appearance, dialogue/speech, inner thoughts, action, and reaction. Characterization is a process authors employ in order to build a description of the character to the audience. It helps readers to understand who the character is and what he/she is like.
In the excerpt we are analyzing here, Kara is the one being described. The method chosen by the author is action. From the actions performed by Kara - yawning and rolling her eyes - we can tell she is probably utterly bored by the lecture.
