In the last year more than 20 teenagers have died as a result of knife attacks in the UK - that's almost one teenager every two weeks.
In 2003, 14-year-old Luke Walmsley died after he was stabbed by another pupil at Birkbeck School in Lincolnshire.
It's illegal to have knives at school and it's important to remember that deaths like Luke's are very rare.
But according to police more and more of you are carrying knives - sometimes with terrible consequences.
Kirsty, 14, from Scotland was involved in a fight with a friend and ended up being slashed with a knife.
She told the BBC's Panorama programme she was cut on the cheek and forehead and needed to have 93 stitches.
Kirsty is one of a growing number of children who are victims of knife crime - often for the most trivial reasons.
It's a problem affecting the whole country, in cities and in the countryside, and many feel it's getting worse.