Replacing a missing tile
A missing ceiling tile can lead to a range of problems. If you have a rat infestation, those creepy creatures can come crashing down from your ceiling and onto your beautiful rugs. Or a teacher may find a way to hide in the ceiling and spy on their students during tests. The point is, you should replace a missing ceiling tile right away.
But if you don’t have the time or energy, or if you can’t find the right kind of tile, what you can do is take one of your existing tiles down, Xerox it, and use the copy to cover the open gap. Simple, cheap, and ingenious.