What excuses does Peggy think up for her behaviour? Why?

Peggy had told Maddie with pretended casualness that both of them should go and see if Wanda had left the town or not. The excuse that Peggy thought up for her behaviour was that she never called Wanda a foreigner or made fun of her name. She also said that she never thought Wanda had even the sense to know that they were making fun of her. She thought Wanda was too dumb. However, she appreciated the fact that Wanda could draw so well. She was making such excuses because she was feeling bad about what had happened, thinking that it probably was her teasing because of which Wanda left the school.