Equating herself with a glass library shows how precarious Claudia thinks her situation is as she tries to keep her difficulties reading a secret. In addition, she’s also trying not to seem too desperate to find Monday. Lying to Ms. Paul about Monday’s whereabouts, though, indicates that Claudia doesn’t want to accept that Monday is missing and might be in trouble. As a librarian, Ms. Paul might be able to help track Monday down—but only if she knew Monday might need help. In this way, Claudia unwittingly walls herself off from someone who could possibly help her.