I watched the entire judge's summing up of the case.
Khan did not have a good family life. I mention this as the judge took it into account in mitigation of the sentence albeit not by much.
It's worth watching her summing up to understand the chain of events, how things between a group of four boys had escalated, starting out as bullying and racial abuse of Khan, who was new to the school, by someone referred to as Boy X who had threatened to knife Khan.
I am not defending what Khan did. He took a knife to school (he said as protection) but used it to murder the schoolfriend who has sided with Boy X in a row on Snapchat.
The issue is why boys are behaving in this way and the easy with which they can obtain weapons - and get them into school although one might imagine this could easily have happened off school premises.
One life lost and another wasted apparently over a third boy who doesn't appear to have to bear any responsibility.