Why were the children ashamed when they heard Atticus was helping a black man in To Kill a Mockingbird?

Not all of the children in To Kill a
Mockingbird were ashamed that Atticus had taken on the responsibility of
defending the black man, Tom Robinson, of the rape accusation against him. Scout and Jem
certainly supported their father, and Dill fell in line with his friends. All three of
them were affected by both the testimony and the eventual verdict, since they had all
come to the conclusion that Tom was innocent of the
charges.

Other children in the story were not so
enlightened. Scout's cousin, Francis, mocked her for Atticus' decision, and Francis
called Atticus a "nigger-lover." Of course, Francis' own opinion was shaped by other
members of his family who thought Atticus was wrong to defend the black man. Cecil
Jacobs was another of Scout's schoolmates who taunted her for the same reason. We can
assume that Cecil's parents also believed that Atticus was betraying his race for taking
the case. Racism was strong in Maycomb and in Alabama, so it was not surprising that
many people believed Atticus had made a foolish choice in taking this particular
client.