The phrase "a stern lesson" is correct and usable in written English.
It can be used when referring to a serious or strict teaching moment, often implying that the lesson was learned through difficult or harsh experiences.
Example: "After failing to meet the deadline, he received a stern lesson about the importance of time management."
Alternatives: "a harsh lesson" or "a serious lesson."
In revising Mr Mollah's sentence, the Supreme Court also taught a stern lesson to the International Crimes Tribunal (ICT), a flawed but popular war-crimes court.
Third and scarcely less important, the decision would give bite to conditionality, sending a stern lesson to the rest of Europe that bail-out terms cannot be flouted with impunity.XVI.
The market may at last be giving China companies a stern lesson in markets economics.
His opponents in the Legislature say Brownback's mantra has failed the state and carries a stern lesson in theory versus reality to other states contemplating the same free-market ideas.
And some language instruction on the Internet includes a stern moral lesson.
The men in the audience might be titillated by the first three acts of these operas – customarily devoted to the woman behaving badly – but could take their wives and daughters, safe in the knowledge that a stern moral lesson would be administered via the gruesome death of the heroine in the finale.
She has to learn "the stern lesson of honor" by leaping to her death.
Connor's parents fight bitterly and loudly while his older brother, Brendan Jack Reynorr), a reclusive stoner, gives the diffident guitar-strummer stern lessons in musical taste.
Magnus Watch: Despite breaking his mother's heart it was a bonanza for Magnus (Emil Poulsen) if we're honest; stern lessons in coaster etiquette, the mother lode of Donald Duck comics, and an angelic request to bring comfort to the sick.
Ms. Woodard gives stern lessons in morals and manners when her in-laws' adopted daughter, a cheeky 11-year-old, recoils at the idea of "hanging out with a whole bunch of black people".
Ms. Woodard gives stern lessons in morals and manners when her in-laws' adopted daughter, a cheeky 11-year-old, recoils at the idea of "hanging out with a whole bunch of black people". When her aunt points out, stupefied, that both of them are in fact black, the little dear responds: "I'm not black!
