I read the Narnia books to my daughter. When I got to that sequence about the Calormen, who are bad guys, and "The Calormenes have dark faces and long beards" I had to stop and explain that in the modern world we don't assume having a dark face makes someone evil. In other words I had to do some parenting.
In high school (this was the 1960s) we read Huckleberry Finn. The enword gets quite a workout. The teacher pointed out, in case we didn't notice, how Jim makes use of the fact that the white kids think he's stupid to outsmart them and get them to do his bidding. In other words did some teaching of the all white kids in my all white high school.