I have worked in many schools, some of them quite rough inner city schools, and I have yet to see a knife or hear about a knife related crime in any of them. Most that you get in most schools is mobile phone theft and the usual bullying plus the addition of cyber bullying in the modern day.

The number of knife crimes, regardless of what the tabloids say, is actually very low and the reasons these stories get so much reportage is because of their relative unusual occurence. Also, any knife incidents are more likely related to gang culture elements, many of whom do not actually attend school at all, than the sort of kids who are at school to be disciplined. When the media is following a story they tend to focus on what they want to report rather than what is actually happening because the complete truth is often not entertaining enough to sell. This causes a skewed perception of an issue.