All the students are ushered into the multi-colored hall, in shades of something between black and white but not grey, and sit (or whatever, some of them don't have legs) on benches. Four professors, all completely human and normal, without any trace of abnormality, stride into the room and demand silence.
With a completely normal microphone, the first teacher speaks. "I am Michael, Professor of Normalcy. Welcome, one and all, to GTS."
Michael passes the mike to the second teacher. "I am Uriel, Professor of Secrecy. I will be teaching you all how to hide your true selves," she says. She adjusts her glasses and passes the mike once more.
"I am Samael," says he, with a dark and brooding face, his sinister voice a perfect match. "Professor of Heresy, and the protection of such."
The final professor speaks, this one much more cheerful. "I am Gabriel, Professor of Ability. Think of me as a PE coach." A lot of aliens and sentient rocks look confused. "Never mind. I'll be taking you all on field trips and missions to determine how well you apply your knowledge." His face suddenly becomes stern. "And I will not tolerate tomfoolery. The last time I let my guard down the dinosaurs were wiped out."
Professor Michael gets the mike again. "That's enough for introductions. Many out-of-school professors may come to speak, so us four are not your only teachers. Please, go to your dorms and common rooms. Classes begin tomorrow." Many of them are confused by the concept of tomorrow. "Never mind."
Now you may all go to your dorms, stay in the hall, or gallivant around. I'll make a map (in human standard) for you all soon-ish.