When Atticus wants his kids to learn a lesson in the book he lets them experience it and learn from them. Now kids are often told what and what not to do. In my opinion this will give a child a more likely chance of doing something wrong because instead of experiencing what they shouldn't do they are told what not to do and they are curious to know what will happen if they do that thing.
In this photo you see white people marching with the blacks in the segregation march. Both kids but mainly scout had live with people who constantly bantered her father because he was trying to help a black man. He was referred to as a nigger-lover.
For fun Jem, Scout and Dill would mess with their neighbor Boo Radley. They tried hard to interact with Boo, but kids now are either to lazy to go outside and be adventurous or their parents wouldn't allow them to be snooping around in other peoples yard
Knowing that there people calling them names and insulting them, Atticus still allowed Jem and Scout to have guns. Now kids do all kinds of things with guns like kill teachers in a school. This show the amount of trust Atticus has with his children