A boy who lied to police after he stabbed a teenager in the heart will spend eight months in custody.
Manchester Grammar School pupil Yousef Makki, 17, was stabbed in Hale Barns, Greater Manchester, on 2 March.
Boy A, also 17, argued he acted in self-defence and was cleared of murder and manslaughter after a trial.
But he admitted perverting the course of justice and possession of a knife and was sentenced at Manchester Crown Court.
Another 17-year-old, known as Boy B, was given a four-month detention and training order after he also admitted possessing a knife.
Yousef, from an Anglo-Lebanese family, had won a scholarship to the prestigious £12,000-a-year Manchester Grammar School and his father said he dreamed of becoming a heart surgeon.
After sentencing, Dr Martin Boulton, the school’s high master, said: “Yousef was an incredibly bright, immensely popular and caring young man, and he is deeply missed by those who knew him.”
The trial heard the stabbing in the village, which is popular with footballers and celebrities, was an “accident waiting to happen” as all three teenagers had indulged in “idiotic fantasies” playing middle-class gangsters.
Sentencing, Mr Justice Bryan said “knife crime is a cancer on society” and the boys had been involved in a “warped culture where the possession of knives was perceived to be cool and aesthetically pleasing”.
They had “an unhealthy fixation with knives which is all too common amongst the youth of today”, which was “a recipe for disaster” when mixed with drugs and drug dealing, he said.
Mr Justice Bryan added: “The message that must be brought home is that knives kill, and knives ruin lives.
“The best legacy of Yousef’s tragic death would be if this message could be got across – and knives [are] regarded as ‘uncool’ by the young in society going forward.”
The judge sentenced Boy A to a 12-month detention and training order for perverting the course of justice, and a four-month detention and training order for possession of a blade, to run consecutively.
Both defendants were cleared of conspiracy to commit robbery in the run-up to Yousef’s death, while Boy B was also cleared of perverting the course of justice.
They will be released halfway through their sentences under supervision.