My younger sister cleaned the room.
I heard that there is a room that only appears at night in the music room of my school.
I can’t clean my room because whenever I try I just get distracted by all the stuff I find.
If you have a part of a roof, that part is your room. Just imagine a roof divided into sections in a house, with the sections going all the way down to the ground. Each section is its own room, right?
The reading is kind of an exception. The 屋 is normal (や) but the 部 is weird. It is へ. Just imagine that you rent out a room and the only one they have is just the hay (へ) room in the barn, so you sleep there for the night. Imagine the smell of hay and how scratchy it is to sleep in this room.