in the book Roll of Thunder head My Cry, explain how Cassie has matured in that time

Cassie is always an intelligent girl both intellectually and emotionally. I think the change is that she becomes much more mature in her outlook. She understands race relations better than she ever has before. She understands the darkness of racial-hatred that her family must endure. She knows what is important and that like the tree in their yard, she must weather the storms. She knows when to pick her battles and when to stand down.