Many of the measures being implemented are reactionary, following a wave of eight serious shooting incidents in US schools over the last two years. More significant and contentious, however, are the ways in which educationalists are working with children in order to identify those kids who might present a danger to others. The school in Michigan where Kayla Rolland was shot dead this month had begun just such a pilot project a year ago, attempting to identify high-risk students.

The Primary Mental Health Project is part of a nationwide programme designed to implement prevention measures by dealing with individuals as young as six or seven years old. The programme, which began in two New York schools 43 years ago, is now being implemented in more than 1,100 schools across 11 states.

However, feelings on the efficacy of the programme are mixed. Some districts in Illinois have opted out of aspects of the programme, expressing fears that labelling children as "high risk" when they are six or seven years of age may stigmatise the children and damage other areas of their development.

"Some schools and districts have decided that it may be harmful to children to intervene on the basis of speculation," said a spokeswoman for the Chicago public schools network. "They have decided that it is hard and possibly harmful for a child to be identified as a problem at such an early age, and in those areas we have different schemes wherein we study the actual potential for violence of kids who make threats, look at what their needs are. The idea is to go beyond mere background flags in identifying kids who may present a risk and to look for patterns of actual behaviour, such as bullying, in the classroom as a warning signal. The aim is to avoid labelling a child merely on the basis of environmental factors."

Although there are variations in approach to identification of problem students, and to the precise timing of interventions, there is agreement that the solutions lie in the long term not in increased surveillance or men dressed up as birds but in putting skilled professionals to work with children on an almost constant basis.

This system involves teachers and social workers working with the child to build confidence and trust and to provide an ear receptive to the child's frustrations and problems.

Officials in Michigan have declined to say whether the six-year-old who brought a gun to school with such sad consequences had come under the auspices of their programme. The use of such programmes has produced results however almost everywhere they have been tried. Nobody knows how many shootings have been prevented, but the empathy and care taken with young children has produced better grades and attendance figures as a by-product.

Americans are trying hard to keep their schools safe, but the bigger picture often eludes them. I spent time last December with Dr John Barrett from Cork, who is head of the trauma unit in Cook County Hospital in Chicago. His life is devoted to removing bullets from people. He spoke from the trenches about the issue of gun control - Littleton, Colorado, was still on his mind.

"The effects of a Littleton are short term. Some white children in Colorado are killed and for a week the overwhelming tragedy of that situation focuses attention on the issue, but the overall problem never gets dealt with.

"The number of deaths because of the gun culture we have here is too big for people to absorb I think. There will always be deaths when guns are so widely available."

So you always wonder if the bubble you keep your child in can easily be popped. Our best friends in Chicago run a jewellery store. Their daughter shares a class with our younger girl and the kids often pop into the store on their way home from school.

You find yourself wondering quietly: would a jeweller keep a gun handy?

How handy?

Our two daughters have benefited greatly from their year in the Chicago system. By happenstance we came upon a school which is diverse, rigorously academic and constantly challenging. Still you worry, and still you are left to ponder how far the ripples of gun culture carry.

Last week, seven days exactly after Kayla Holland was shot by a classmate in Mount Morris Township in Michigan, our six-year-old indignantly reported a schoolyard incident to us: an eight-year-old had pushed her and her friend out of the queue for the slide - "Hey Sis, out of my way," she said.

Scarcely bloodcurdling stuff. A year ago, though, I'd have urged our little one to stand her ground next time it happens. Last week I kissed her head and told her these things happen. Leave it alone, I said, it could have been worse.