Think of this as a prologue. Chapter 1 (Dursley Overdose) and Chapter 2 (The Hat's Speech)
A letter sent from Albus Dumbledore to all faculty and staff at Hogwarts School for Witchcraft and Wizardry:
Dear Faculty and Staff,
I hope you have had a pleasant semester, and that preparations for classes after Winter Break are going splendidly. I hate to add more pressure to your already busy lives, but new Ministry precautions for all schools have just arrived. Apparently news of Voldemort He Who Shall Not Be Named returning has been around. Obviously these are just rumors, but we may as well humor the Ministry.
Here is the first of three major changes: All classes must be recorded. From your teaching, to students questions. Every word said must be documented. Have each child try to do the best they can. You may not look at this, and each student's reports must be sent directly to me. I will organize them for the Ministry. The point of this is so that the Ministry knows what we're teaching and whether students know enough defenses. Remember, the Ministry doesn't want anyone to know about this, so please do not say anything about this to anyone.
The second precaution: We have been entrusted with an important magical object. I would like each teacher to produce a spell, a challenge if you will, to stop any would-be thieves from entering.
The third precaution: A threat has been made against Hogwarts. Here is what I want you to do…