Characters: Sirius and students/staff who want to come along.
What: ...exactly what it says on the tin? SAFETY FIRST, KIDS.
Where: A classroom that is extremely easy to find because Sirius has, true to his word, set up little signs. Also there's a nameplate tacked to the door.
When: Slightly forward-dated to the 27th.
Warnings: ...Explosives?
Anyone who enters may notice the classroom is extremely roomy. And mostly white. It has more of a palace-esque feel than anything else, but there are plenty of benches-with the appropriate supplies-for students. and possibly staff.
The only wooden bench in the room is out the front, in front of the blackboard; Sirius is seated behind it, calmly reading. His helmet is off; surprisingly, he looks much like a human. His face is unnaturally pale (or maybe he just hasn't gotten enough sun) and his hair is pure white, but other than that he seems perfectly normal.