Muggle studies was a subject he DID learn at Charms school and he finally went to a class without feeling like a complete failure of not knowing anything despite being a fifth year. As he finally found the classroom on the first floor after following a couple of students he overheard talking about the subject. He entered the room with his wand at the ready. One thing he learned at this crazy school was that 1 a student had died last year and 2 the Professors were putting them in crazy unexpected tasks whenever they walked in to a classroom.

Flamsteeds SHOUTING and PLANET EXPLODING in their faces and Bellaire literally dropping them in the wild . “Survive mwahahaha” kind of thing.

So yes, Yoongi was not entering this room unprepared. Only, upon entering he realised that this was probably the most normal classroom he had seen so far and he lowered his wand, still not putting it back in its holster though. “Hello Professor” he greeted with a smile as well before walking to an empty seat and sat down