In Chapter 4 of To Kill a Mockingbird, we learn that Atticus went to school at home. Does this mean he didn't go to school? Reference in the...

You're correct to assume that Atticus had no formal
schooling when he was a young boy (although he did go to law school as a young adult). 
In Chapter 3, Scout complains about her terrible first day of school and tells
Atticus,

You
never went to school and you do all right, so I'll just stay home too.  You can teach me
like Granddaddy taught you 'n' Uncle
Jack.

It wasn't uncommon for
children to receive their educations at home--from their parents--during the time period
in which Atticus would have been a boy (the late 1800s).  However, Atticus reminds Scout
that laws have changed--and that he would end up in jail if he failed to send Scout to
school.