A 16-year-old boy who stabbed a fellow pupil near Nottingham Academy has been sentenced to 18 months at a youth detention centre.
The victim, also 16, was attacked near Coppice Park, in Ransom Road, St Ann's, on the morning of 14 May.
The offender, who cannot be named because of his age, gave chase after waiting at the park for the boy wearing a mask, Nottingham Crown Court heard.
He admitted grievous bodily harm and possession of an offensive weapon.
The defendant also pleaded guilty to possession of cannabis.
The court heard that the victim was walking to Nottingham Academy, where he was due to sit a GCSE exam.
His attacker was waiting for him wearing a black mask at the park entrance. The victim ran away, but the offender gave chase.
There was a scuffle and the teenager was stabbed twice, once in the hip and once in the buttock. The court heard the attack happened because the pair had fallen out.
The offender claimed he was carrying a knife for self-protection because he had experienced bullying in the past.
Judge Gregory Dickinson told the defendant that although he was only 16 he had already made the "worst decision" of his life by carrying out the attack.
He acknowledged the schoolboy was of previous good character, had academic potential and was capable of a better life.
The judge added that he would have faced seven years in prison had he been an adult.
Nottingham Academy said it took pupil safety "extremely seriously" and had carried out "a huge amount of work to instil positive values in our young people and promote 'respect values'".
A spokesperson said: "Since this appalling incident, the academy has also hosted two meetings to allow community representatives, including police, youth services and our school, to come together with parents to discuss issues and solutions, and which provided a forum for parents to raise any concerns they may have.
"These have been very positive and we will continue to work hard with all partners to ensure our young people are kept safe."