In To Kill a Mockingbird, what did Jem do that made Scout say "he broke the remaining code of our childhood"?

Part of
growing up is being able to figure out what is right and what is wrong, especially if there will
be serious consequences for not doing what is right. For , this means turning in the runaway
Dill, who is hiding under s bed. Dill feels at home in Maycomb because of the unique friendships
he has with Scout and Jem, and he also admiresfor being the type of father he never had.  Poor
Dill feels unloved and neglected by his own family, who doesnt seem to have time for him.
Maycomb is a refuge for Dill where he feels wanted and appreciated by his friends.  

Jem telling Atticus about Dill running away and hiding breaks the code of childhood
where you dont rat on one another. For example, Dill covers for Jem when Jem loses his pants
to the Radley wire fence, and it is an unstated rule of childhood to not tell on each other even
if you have to lie. However, Jem understands that Dills disappearance is dangerous, and Dills
family will probably be in a panic over where Dill is. Jem shows that he is growing up and is
learning to make adult decisions that supersede any kind of childhood pact that he once
made.