Lockdown drills are scary.  They can have lasting effects and leave children feeling vulnerable and scared.   This is exactly how Ava feels.  Grandad says, that is okay.  When he used to do Duck and Cover drills, he too felt scared.  So, they talk over how to feel better and what to do with these feelings.  I hate that books like these need to exist, but they are needed.  This one does an excellent job of letting the reader know their feelings are valid and allowed. The author even puts her own story of being in a school lockdown at the end of the book.