Why does Atticus give a lot of advice to Scout and Jem?

Atticus gives his two children, Jem and Scout, a lot of advice for several different reasons.
First of all, both Jem and Scout are bright and inquisitive, and throughout the duration of the novel, it is clear to the reader that they are living in confusing times, surrounded by confusing events and people. Atticus gives them a lot of advice perhaps because they need the advice in order to manage all the challenges presented to them in the novel.
Second of all, Atticus is a single father, so he must take on the role of two parents so that Jem and Scout feel supported. A mother may have given both children sensitive and thoughtful advice like Atticus does, but as she is a missing presence in the children's lives; Atticus must do it all himself.
Third of all, Atticus has made some decisions, like the one to defend Tom Robinson, that impact his children's lives directly. Perhaps Atticus feels responsible for some of the difficulties they are facing as a result of this decision, and so Atticus offers them helpful advice to ensure they survive the situation he has created.