The teacher said many pupils have “no intention” of harming people but carry knives through fear they themselves will be attacked.
“I had the opportunity to ask a pupil why they had brought a weapon to school – they told me they had no intention of using it, but other people on the streets had them,” she said.
“This was otherwise a good kid.”
The seizures highlighted the scale of the problem needing to be dealt with to keep children safe within and outside schools, Mr Roach said.
“No young person should feel the need to carry a weapon.”
GMP schemes to tackle youth knife crime include Forever Amnesty, which set up 13 anonymous knife bins in the region.
The force has been invited to comment on the data.
