Teachers' Job Description; or, The Nature & Purpose of Education Revealed

And that was the trouble. If you didn't find some way of stopping it, people would go on asking questions. The teachers were useful there.... They taught children enough to shut them up, which was the main thing, after all. But they always had to be driven out of the villages by nightfall in case they stole chickens.

-- Terry Pratchett, The Wee Free Men, Chapter 1

Plus! Bonus quote from the subsequent lesson:

"Zoology, eh? That's a big word, isn't it."
"No, actually, it isn't," said Tiffany. "Patronizing is a big word. Zoology is really quite short."

-- Ibid.