Before the murder on 3 February, Khan and Harvey had taken opposite sides in a separate conflict between two other pupils, which led to the school being briefly locked down on 29 January.
During the trial, the jury was played CCTV from the day of the stabbing, which showed the killer approaching Harvey in the courtyard shortly after midday.
The pair stood for a moment, appearing to talk, before Khan pulled out a knife and stabbed Harvey in the chest, severing a rib in the process.
The trial heard from fellow pupils who described a scene of “chaos”, as people “were running, screaming everywhere”.
Khan had told jurors he had not intended to kill Harvey or cause him serious harm, claiming he could not remember what had happened.
He said he had “snapped” and “lost control” of his actions, adding that he had been bullied and could “get angry quickly”.
He said he had experienced racist abuse and taunts on social media about a medical condition, and that he had been neglected and suffered physical and emotional abuse at home.
However, the prosecution said he had “wanted to show he was hard” and “knew exactly what he was doing”.
They said he had an “unhealthy interest in weapons” and had looked up “zombie killer knife” and other blades online, and had also taken pictures of himself with weapons, including a knife and axe, to warn people to stay away.
