For the first several chapters of the story, it is difficult to tell exactly how old Sarah is. We assume from context clues that she is not yet a teenager. She is frightened when the police enter her house and this makes her more timid, rather than angry or cunning. Her mother scolds her and tells her she must do as she is told. And, of course, we know that she is small enough to fit in what her brother calls, "our secret place" (8).
A few chapters later, just after Sarah has her head shaved in the camp, she recognizes the police man from her neighborhood and knows that he recognizes her too. Here, we learn that she is ten years old:
He could only look back at her, motionless. The girl smiled, a bitter smile for a child of ten, and brushed off his heavy hands. (82)