To me, there are a number of important things we can learn from Chapters 11 and 12.
First, I think that we can learn that people in good families love each other through the good times and the bad. We see this in how the Curtis boys are able to finally get through the issues they have been having.
I think the most important thing we can learn is that we should not give up on ourselves. Pony learns this at the end of the book. He learns that he must not give in to pessimism or despair. Instead, he has to fight through his problems so he can stay gold.