What valuable lesson(s) does Jem learn in the story? How do you know this?

Jem learns that rumors cannot always be believed, as they are often bot what they seem to be. He learns that there are times that justice will never be served, and that no matter what Atticus did for Tom, his fate was already sealed (he also comes to the conclusion that juries should be abolished). And lastly, he learns that his father is someone he can be proud of and strive to emulate.

Great.