Short story, boy at a boarding school gets in trouble for telling the truth about why he was late to class

[Brian]

Read this in the early 80s, though probably a lot older. The boys at a boarding school (in England?) know that if they're late to class, they just have to tell the teacher they were at early mass and they'll be believed. One day the narrator, for reasons he doesn't understand, tells the truth about why he was late: he'd been out messing around. The teacher seriously punishes him and his classmates are furious, afraid that his truthfulness will make the teacher see through their lies. The next time the narrator is late, he goes with the 'early mass' line and is believed, because he'd been inadvertently taught that's it's better to lie than to be honest. I read this in a compilation textbook.

[Daisy]

I don't think The Adventures of Tom Sawyer is your book, but it has a kinda-similar incident: when Tom is late for class, instead of making up a lie, he tells the truth - he was hanging out with Huck Finn - because he wants to be punished, because the punishment would be to sit on the girls' side of the room, and the only empty desk over there is next to the lovely Becky Thatcher.