Their residents who sleep in are taught a lesson (8,7)

I believe the answer is:

boarding schools

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This might be a double definition.

'their residents who sleep in are taught' is the first definition.
I know that 'taught' relates to this answer.

'a lesson' is the second definition.
Although both the answer and definition are nouns, they are not in the same form of the noun. However, I know that 'lesson' relates to this answer.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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