A teenager accused of murdering a promising 15-year-old footballer has gone on trial at the Old Bailey for a second time.
Teachers described Kiyan as a very popular and well liked pupil
Kiyan Prince was stabbed outside his school in Edgware, north London, when he intervened in a fight on 18 May.
The 16-year-old defendant, who cannot be named, has admitted stabbing Kiyan, but denies it was murder.
A jury could not agree a verdict when the boy appeared in court earlier this year and a retrial was arranged.
The defendant and another boy were play-fighting when Kiyan told them to "stop playing around", the prosecution alleged.
The defendant went up to him and said: "What's going on?"
He then pushed Kiyan, who pushed him back, according to the other boy.
As the defendant stepped back, the boy said his hand went to his pocket.
Kiyan asked "What is that?" and the defendant told him he would hit him or do something if he pushed him again, according to the other boy.
When Kiyan did push the defendant, the other boy saw that the 16-year-old had a knife.
Kiyan, 15, who played for Queens Park Rangers' youth team, was in Year 10 at London Academy, Edgware, and was described by a teacher as a "gorgeous boy, very popular and well liked by all who knew him".
The trial continues.