Judas window
n.— «Classroom surveillance is nothing new. Most classroom doors have a glass section—a Judas window in chalkie parlance—allowing management to surreptitiously spy on Sir’s lesson.» —“Yes, head boys must have the latest toys” by Hugh Reilly Scotsman (Glasgow, Scotland) Mar. 9, 2005. (source: Double-Tongued Dictionary)
Further reading
What kind of book do people ask for most often in prison? Romance novels? No. The Bible? No. The most requested books by far are … dictionaries! A number of volunteer organizations gather and distribute used dictionaries to help inmates with...
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...