How does Harper Lee mock the educational system in To Kill a Mockingbird?

Scout's class is lectured about Hitler's persecution of the Jews and on the virtues of equality and democracy. The satirical points are made by Scout who asks Jem how Miss Gates can preach about equality when she came out of the courthouse after the trial and told Miss Stephanie Crawford that "it was about time that someone taught the blacks in town a lesson". This reveals the education system at that time to be as hypocritical as the missionary circle (in Chapter 24).