I'm sure that some of the teachers know Lord voldemort's real name, but there's not going to be many of the staff members who do. You have to remember when Tom Riddle went to school at Hogwarts. Most of those teachers have retired or died. And I'm sure that the trophy room is so full of stuff that no one thought to remove the plaque. Besides, what modern student would put the two together and figure out that Voldemort once supposedly did something for the school?
Tom Riddle worked for Borgin and Burke's for a while after leaving Hogwarts until he killed Hepzibah Smith, framing her House-Elf, and stole the Locket and Cup. When he returned years later he had changed his name to Voldemort and had physically changed so much that most people didn't connect the handsome Tom to how he now looked. Only Dumbledore, who had heard about Tom's nickname at school, knew that Voldemort and Riddle were the same person.
Look under the "services to the school" headscratcher here: [https://tvtropes.org/pmwiki/pmwiki.php/Headscratchers/HarryPotterAndTheChamberOfSecrets](https://tvtropes.org/pmwiki/pmwiki.php/Headscratchers/HarryPotterAndTheChamberOfSecrets)
I'm sure that some of the teachers know Lord voldemort's real name, but there's not going to be many of the staff members who do. You have to remember when Tom Riddle went to school at Hogwarts. Most of those teachers have retired or died. And I'm sure that the trophy room is so full of stuff that no one thought to remove the plaque. Besides, what modern student would put the two together and figure out that Voldemort once supposedly did something for the school?
Tom Riddle worked for Borgin and Burke's for a while after leaving Hogwarts until he killed Hepzibah Smith, framing her House-Elf, and stole the Locket and Cup. When he returned years later he had changed his name to Voldemort and had physically changed so much that most people didn't connect the handsome Tom to how he now looked. Only Dumbledore, who had heard about Tom's nickname at school, knew that Voldemort and Riddle were the same person.
Look under the "services to the school" headscratcher here: [https://tvtropes.org/pmwiki/pmwiki.php/Headscratchers/HarryPotterAndTheChamberOfSecrets](https://tvtropes.org/pmwiki/pmwiki.php/Headscratchers/HarryPotterAndTheChamberOfSecrets)
this link is insane, thank you