This page of our guide to Psychonauts 2 lists the Memory Vaults available in Cassie's Collection.
Two Memory Vaults can be found in this level.
Cassie's Escape Plan
Location: Deep Inside Teacher's Domain.
You'll come across this secret during a fight. Just aim at the escaping Memory Vault to make it get into your inventory.
Protect the Queen
Location: Exhibit A.
To get to this secret, you have to jump on a stack of books. Then, hit the escaping object several times to get it to your inventory.