Home Secretary Jacqui Smith has announced that metal detectors will be used in some schools to try and prevent pupils bringing in knives. Like all ideas we need to think about how it could actually work in practise.
Let's assume that it takes on average 30 seconds per child (by the time they've triggered the damn thing with pencil sharpeners, belt buckles, watches etc and had to go through again, then triggered it again, then refused to go through it again, stormed off and returned with their mother who will want to complain about radiation, rights or something...)
Let's also assume that we are given two detectors so that we can use two entrances at the same time. With our 900 pupil school, we should be able to get everyone inside in just 3 hours and 45 minutes. So if we can make a prompt start at quarter to nine, then we will be finished by 12.30 just in time for lunch. Pupils found to be carrying knives will then be given a 20 minute detention. (Attendance optional)
Let's not hear any talk of ceramic knives, baseball bats, or chair legs and don't even think about windows or Fire Exits.