Hatred and prejudice
The main theme that drives the plot of the novel is the theme of hatred as well as prejudice. Mr. Griffin is not a good teacher, despite the fact that the ending shows his notes of praise towards Susan. His approach towards his student is the one of hatred and prejudice. He demotivates them by humiliating them and pointing out their mistakes and ignoring their successes. It is a toxic and unjustifiable way of teaching. This, by no means, justifies the horrible things the students do to him. The students are filled with hatred and prejudice in their own way. Failing to reflect upon themselves, they externalize the blame and express frustration on this teacher they dislike, leading them to commit heinous acts.
Crime
The novel basically shows a crime and how difficult it is to get away with it. The students kidnap Mr. Griffin and take him to the mountains to scare him. As a result. Mr. Griffin dies. To try to cover up the crime of kidnapping, they commit the crime of hiding the body. After the body gets discovered, they try to cover up their involvement by hiding the evidence, which is, of course, discovered by someone. That someone is David’s grandmother, and now, another, and even more extreme crime takes place, namely, murder. The students are only digging themselves into a deeper hole, which they can’t get out of, and are expectedly caught in the end.
Compassion
Kathy Griffin, Mr. Griffin’s wife, comes into play as the character that shows the most compassion and human decency. She rescues Susan, despite the fact that she was the key component that led to her husband’s death. It shows how, in the moment of their rage against the teacher, the students didn’t consider the consequences. The lack of empathy, and humanity for that matter, was tangible. Once the decision to kidnap Mr. Griffin was given life, compassion and humanity within those students died, and Mr. Griffin’s humanity was stripped away from him.