Atticus makes Jem read to Mrs. Dubose so he will understand the meaning of real courage, because Mrs. Dubose is very ill and is trying to die without morphine.
After Jem ruins Mrs. Dubose’s flowers, Atticus makes him go to apologize although Scout is sure that he will be murdered with a Civil War relic.
Scout is angry at Atticus for sending Jim to Mrs. Dubose. Atticus explains that the summer is going to be difficult for them, and tells her that she will understand when she is older.
[When] you and Jem are grown, maybe you'll look back on this with some compassion and some feeling that I didn't let you down. (ch 11)
Atticus knows that Mrs. Dubose is only the beginning. The children are going to have to face ridicule from both adults and children over Atticus’s defending Tom Robinson. He wants the children to learn courage, and he thinks that Mrs. Dubose is a good example of it.
I wanted you to see something about her- I wanted you to see what real courage is, instead of getting the idea that courage is a man with a gun in his hand. (ch 11)
Atticus wants Jem—and Scout—to realize that courage is more than bravery in the face of danger. Courage is when you have a difficult situation and you still try anyway. Courage is not giving up. He is trying to show them this lesson with his trial.