Originally Posted by The Narrator

All seems to be as it should in the Potions laboratory; however, those who need to use a certain item might notice that they have decreased in number.

Glancing over at the shelves you may notice that several phials that were there just the day before are nowhere to be seen. Perhaps someone recently used them for a fairly large brew? Or maybe the house-elves had taken them for cleaning?

Nothing has been recorded in the logbook and, for those that try, summoning them proves ineffective. Where, oh where, could those missing phials have gone?

If you have your own phials or just don't care to pay attention to such minor things, you would be totally oblivious that anything in the room is missing.

Originally Posted by The Narrator

All seems to be as it should in the Art classroom; however, those with a keen eye might notice a few items that are not in their usual place.

Though this particular room isn't always the best organized due to the number projects and supplies laying about, but those wishing to paint at the smaller tables will find that some of the jars that were used to hold a variety of brushes are now empty.

Looking around, not a single brush can be found on the floor. Maybe someone took them for cleaning and just forgot to return them?

There are a handful of brushes on the large table in the middle of the room though, so maybe you didn't notice that any brushes were missing after all.

Originally Posted by The Narrator

All seems to be as it should in the library; however, those in search of particular titles might have a difficult time scouring the shelves.

Even though books are checked out of the library every day, four books in particular are nowhere to be found. If you need of one of these books for a homework assignment, you will be out of luck as their spots remain vacant.

It is a possibility that someone checked out one of these books, so asking the librarian might be beneficial so you can get in touch with the borrower. But it'll be rather puzzling when the records won't indicate that these books hadn't been checked out.

Where could those books have wandered off to? It wasn't that common for books in the library to go missing, was it?

Originally Posted by The Narrator

All seems to be as it should in the boys' bathroom; however, those needing to relieve themselves in any of the stalls will soon discover otherwise.

Because taking care of your business being your priority, one might not notice right away that something rather essential is missing from all of the stalls. What a surprise it'll be once you realize that there is nothing to wipe your bottom with.

Did the house-elves forget to replace the toilet paper? Or had Peeves been here recently and this was one of his nasty pranks?

Regardless, you are in quite a predicament. Dare you ask if someone can find some toilet paper for you? Or do you find another means to clean yourself?