Samantha "Sam" Cooke is a very troubled and naughty girl. That is until she ends up in the care of Brooke Green, who manages to reform her back to her good ways. She starts out as a third grader. And then in the main story's last segment, she becomes a fourth grader.
Then nine years later, she is a high school senior three weeks away from graduation.
Sam's age:
8 years old (Segments 1-7)
9 years old (Segment 8)
18 years old (Epilogue)
Note: I am NOT American, I am actually British. And it's because I've set the story in America that the word "behaviour" is spelled without the "U".