Question

Why does Scout and Jem call Atticus by his name instead of dad?

Answer 1

So it and Jem call Atticus by his name, instead of dad, because it is a sign of respect, they refer to be more formal with their father and it shows that Atticus and his children view each other as equal to each other.

Answer 2

Scout and Jem are more formal with their father and find it more appropriate to call him by his first name. Scout mentions that she has a courteous father but he is sometimes distant.