Since I don't want to interrupy your wonderful RP as of now, and you obviously don't need me to, I will just post here once in a while with some fuel for your imagination. Some teachers you might have met, ideas for students you can encounter, stuff like this. For now, two subjects:
A. Plot element idea: The Ministry of Shadows: I referred to them earlier, but it would make sense for me to also explain to you as plyers what I meant. Maybe your characters know that, maybe they don't(If they grew up in the human world, they almost certainly don't. If they grew up Invisible, they probably do).
The Ministry is an organization who's job is, as you might have already guessed, to protect humans from Invisible dangers and, to a degree, to protect denziens of the Invisible from humans(For example, by taking problematic young monsters to a place where they won't attract unwanted attention). The Ministry is pretty much what you would call the "men in black": they are the mysterious, sunglasses wearing guys who work for some unspecified government agency, who's job is to erase memories, destroy evidence, and sometimes hunt down rogue supernaturals(thaugh they prefer not to if it is at all means possible). They work mostly behind the scenes, unknown to world leaders or to the public. They manipulate things from a distance. Everything is very subtle, very secretive, very hush-hush.
Of course, when there IS a need for violence, they do that, too. While most agents for The Ministry are humans "in the know", a significant portion are psychics, warlocks, mad scientists and oracles. They have access to a lot of supernatural resources, and they are not afraid to use them.
Ministry agents are often referred to as "shaders". While in the field, they often use "colored" codenames: "Mr Brown", "Mr Black", "Mr Grey"...
B. Idea for a teacher: Mr Oaken:
One class alwayes takes place in a small gaden within school grounds. The place is quite and beutiful, with some benches, flowers, you know how gardens look. In the center of it, thaugh, grows a huge, ancient oak tree with red leaves. Those who sit beneath to rest or speak find the ground almost supernaturally comfortable, as if the roots and thorns and the small stones that lie everywhere in the grass have just stepped aside a little just for them. The wind here is more pleasent, and moves the old branches in just the right way to create nice, cool shadows.
Most don't find the tree very interesting, thaugh, until they get to go to a class thaught by the very appropriatly named "Mr Oaken"(It's not his real name, some may say, but it fit so well it simply stuck): you understand, the tree, thaugh it no longer has eyes or ears like ours, sees and hears very well what goes around him. When he wishes to speak, sometimes, with the sound of old, cracking bark like a wooden moan, the branches and stamp move around and twist to create what looks like the face of an old, old man with a beard of red leaves. With a voice of the wind whispering between the branches, the tree man speaks. Once, some of the teachers say, he only spoke in playful rhymes and wise riddles. He is getting older, thaugh, and his mind is not as sharp as it used to be, so this becomes more and more difficult, frustrating him to no end. He likes to tell to all who would listen that long, long ago he was a ghale, a forest spirit of the seelie court, and a resident of the nearby woods. He was ancient, thaugh, approaching the final years of his life, the autunm of his immortality, and one day, while walking around in this very place(then a part of his wood) he became so tired of this all he decided to just sit down and rest for a while.
A while happned to be four hundred years, thaugh, and when he woke up, he found that he had become as he is now: a fae oak, mighty and majestic. He liked it far better this way, and when he found out that in the time some people decided to build a garden and a school around him, he was happy to work as a teacher of faerie history and magic in return for being regulary watred and tended to. Thaugh he can be somewhat cranky sometimes(as expected of someone his age), in the end of the day he likes children and he likes teaching children, and is very happy about the whole situation.