What is the literary term for this technique of hinting at things to come, such as when Aaron smiles up at Hannah in The Devil's Arithmetic?

Aaron’s smile is an example of foreshadowing, when an author hints at the future.

During the reading of the four questions, Hannah’s little brother Aaron is nervous.  He thinks he is going to forget something.  Hannah remembers how she used to be nervous the first time she did it, and she tries to distract him.  During the remembrance, she gives him encouragement.  When a page gets flipped, she helps him.

Hannah reached out and smoothed it back for him and he smiled up at her gratefully.  He has the greatest smile, Hannah thought… (ch 2, p. 14)

This incident demonstrates that Hannah is caring and forgiving.  She worries about her brother, and has empathy for him.  His fear and her reaction foreshadows the coming events, because Hannah is the only one who knows what is going to happen in the Holocaust during the book.