Why does Atticus tell Scout that she can continue to read with him each night?

In the book, To Kill a Mockingbird, Scout comes home for lunch from school. She is just starting school and is quite a tomboy. However, she did not have a good first day. She got in a fight at school with a boy and her teacher told her that she could only read in school.

She and her father had been reading together at night. Her father, Atticus, takes Scout outside and talks to her on the swing that is on the porch. Since Scout is upset and realizes that she does not like school due to her bad day. So, Atticus convinces Scout that they will go on reading together each night if Scout continues to go to school. Scout agrees.