Gringotts Wizarding Bank
All of my students have their own bank vault page where I keep track of their accounts. On their first day at Hogwarts they randomly selected a key to a vault. The vaults all belonged to famous wizarding families and have been passed on to whomever owns the key. The students now own the key, so they get to inherit the vault and keep whatever was left inside. So, for example one student choose the key for vault #713. This vault belonged to Nicolas Flamel and contained 10 galleons.
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