The mother of murdered schoolboy Luke Walmsley has said it should be easier for schools to expel those like the "evil bully" who killed her son.
Jayne Walmsley: "Older boys often picked on Luke"
Jayne Walmsley said weapons detectors in schools, as suggested by a teachers' union, would be going too far.
But she thought there ought to be central funding for closed-circuit TV in all school areas.
Mrs Walmsley was speaking at a news conference following the sentencing of her son's killer.
He has now been named publicly as Alan Pennell.
A judge at Nottingham Crown Court said he should serve a life sentence, of at least 12 years.
'Too many chances'
Jayne Walmsley said: "He was just an evil boy who was a bully.
"He roamed in a pack, he is a true bully, and I don't think the school has enough power to get rid of these people."
She said she believed such pupils were given too many chances before being thrown out of school - which was not the way things were in adult life.
In the area of her son's school, Birkbeck College in North Somercotes, Lincolnshire, disruptive children "just seem to be moved from school to school".
"It's wrong," she said. Pennell should have been expelled and sent to a special unit.
Mrs Walmsley said that in this case, CCTV in the school had been used only as part of bringing him to justice.
But there had been no cameras in the locker areas or in the alcove where Luke was fatally stabbed.
"Every school should be provided with good CCTV throughout the school," she said.
This "should not have to come out of funds", it "should be provided".
But Birkbeck College was "a good little school" - a small rural community and not the sort of place where such a murder might be expected.
She hoped the local education authority's inquiry into the killing would "delve deep" and seek a wide range of opinion about the lessons to be learned.
Earlier, the NASUWT union had repeated its call for pupils to face random security checks using X-ray equipment to stop them bringing knives and guns into school.
"This seems to be an example of the growing weapon-carrying culture, that is rife on the streets, now spreading over to schools, which have been relative havens of peace and security," said acting general secretary Chris Keates.
"NASUWT has called for random airport-style security checks in schools. This would act as both deterrent and a way of monitoring the extent of the problem."
But the Secondary Heads Association said that the murder, though very distressing, was very unusual.
Deputy general secretary Martin Ward said: "I don't think that we have called for any changes in policy. What we have to remember is schools are extremely safe places.
"That is exactly why this has made news headlines. They are far safer than the streets and parks which children use at other times."
A spokesperson for the Department for Education and Skills said: "Our thoughts are with Luke's family and friends at this very difficult time.
"In the coming months, we will consider any lessons to be learned, and whether further action can be taken to enhance school security."
There were now 370 police officers based in schools in England.
A total of £470m was being spent on tackling bad behaviour, bullying and truancy and since 1997 £120m had gone into making schools more secure.
It was already a specific criminal offence to carry a knife on school premises.
Head teachers had the power to permanently exclude students for violent offences, and the rules had been tightened to stop them being readmitted on technicalities.