Lesson One (Year IV)

Ambrosius stood quietly before the wall, contemplating the immense moving tapestry that decorated it. In his entire existence, he had rarely seen anything less gracious than a group of trolls gamboling by a forest clearing in short pink skirts. 

As faint footsteps echoed through the seventh floor corridor, he turned around and gazed down the dimly lit hallway. He had informed his fourth year students to meet him here exceptionally for their next lesson, and some of them were apparently arriving.

James climbed the staircase leading to the seventh floor, Professor Umbranox's note in his hand. Following the instructions, he walked through the obscure corridor, yet it seemed deserted. He read the message one more time, anxious that he might have misunderstood the directions. 

The sight of the teacher's tall figure reassured him. Silently nodding at him, he leaned against the wall and looked around. Apart from a large tapestry, there seemed to be nothing of note in the hallway, and he could see no door leading to a classroom. Wondering why Professor Umbranox would want to meet them there, he turned around and impatiently glanced down the corridor to check if the others were coming. 

"The change of scenery may be slightly confusing, yet you will understand soon enough." he told the students once they were all there. "Does anyone know where we are?" he inquired, brushing the cold stone surface of the wall with his fingers. "And no, the Seventh Floor corridor is not the answer I am expecting."

James glanced around, confused. There were no rooms, just a bare wall on one side and a tapestry covered one on the other. Shrugging, he turned towards the others to see if they knew more.

"Yes we are." Ambrosius responded, gazing at his students while strolling before the apparently bare wall. "I am slightly surprised to see that you know of it, given that not many are familiar with it. I have only recently discovered its existence myself. Yet I presume that your uncle shared the tale with..."
Another student suddenly hastily arrived, interrupting him. "Have no worries, miss Hazel. I am certain your tardiness is justifiable by completely valid grounds."

After walking by the wall for the third time, he turned to the audience. "Without further delay, behold the Room of Requirement." He was turning his back to the wall, yet the exclamations of some of the students informed him that the door had well and truly appeared. "Perhaps the most amazing and useful room in this Castle, the Room of Requirement, also known as the Come and Go Room, has the remarkable ability to provide one with whatever one desires. You need only walk in front of it three times, envisioning what you require, and the Room will do the rest." he explained. "For those of you who are fond of roaming the corridors after hour - may it be clear in passing that I naturally reprimand such behaviour - the Room may offer you the hiding place you were so desperate to find. And if, like me, you desire to have a classroom large enough for the practical task I have planned for today, once again the Room of Requirement is a perfect choice." Turning around, he faced the heavy iron door and pushed it open. "Now if you would all please come along."

The place was very vast... too vast even. Ambrosius had learned that the Room of Requirement wasn't bound by usual laws of physics, and he decided to use it to his advantage. To ceiling was so high that he had to squint to perceive it, and the whole chamber gave of a sensation of grandeur and sacredness, almost like a cathedral. Despite the strong sun that illuminated the skies, only faint rays of light slanted down from the set of lofty windows that encircled the place.
A massive structure towered to his right. From there, one could only see a ten feet tall stone wall and an entrance leading into darkness, yet Ambrosius knew it concealed an intricate network of confusing pathways and alleys.
However, he guided his students to the other end of the room. A blackboard stood there, surrounded by a few wooden chairs. Not far, a dozen stuffed dummies lined the wall, holding twigs similar to wands.

"Please make yourselves comfortable, take your wands and join me." Before long, they all faced him, ready for the beginning of the lesson. "I know most of you are intrigued with the construction standing behind you, yet I ask you not to be preoccupied with it for now. I will clarify everything when we are done with the first part of the lesson." he said, noticing that some of them were flashing furtive glances behind them.
"Today we are learning what I have no doubt will be one of the most useful spells in your defensive arsenal." he commenced in his calm voice and his habitual serene stroll. "It is common belief among the Ravenclaws that the mind is a wizard's greatest weapon. Yet strip him of his wand, and the sorcerer becomes rather powerless. Of course, the most skilled among us may overcome that difficulty with wandless magic. However, that branch is one of the most advanced of our noble art, and few are those possessing sufficient talent and discipline to master it." As he spoke, one of the chairs got lifted off the ground, slowly spun around in mid-air and then softly landed.

"While I consider all of you to be rather talented for this subject, wandless magic still remains out of your reach. I highly doubt any of your opponents to be well versed in the matter either. Which brings me back to the importance of the instrument you are all holding in your hands, and the usefulness of depriving your foe from it in a duel." He made a brief pause then faced his students again. "Now, would anyone be kind enough to formulate an assumption regarding the subject of today's lesson?"

"The Disarming Charm." Ambrosius confirmed. Behind him, useful information about the spell began filling the blackboard. "Some of you may consider it rather simple, yet I can assure you that it has been extremely helpful to me on many occasions."

Pulling out his wand, he headed towards the line of dummies and aimed it at the closest one. "Expelliarmus" he chanted loudly and clearly. A jet of scarlet light streaked from its extremity and darted at the target. The moment it hit it, the twig flew from its hand, soared high in the air before softly landing in Ambrosius's palm.

"Before we examine the charm in detail, I want you to perform the exercise I have just demonstrated. Be careful though, the incantation and the wand movement are of the utmost importance for this spell. Pronouncing the word wrongly can have a wide spectre of disastrous consequences, ranging from sending your own wand into the air to setting the victim's garments ablaze. And the hand motion must be executed with ultimate precision." He repeated the gesture, a slightly slanted downward line followed by an inward spiral. "Now, if you have no inquiries, you can commence."