It happened Gonegirl many years ago admittedly and before they imposed such drastic health and safety regulations. Child was about 7 kept tipping chair, was warned but didn't stop, chair slipped, he hit his head on one of those old fashioned rradiators with ridges. Lost consciousness and had a large split which bled profusely (as head wounds tend to) ambulance sent for and child taken to A&E, needed stitches. So you may find it funny, but as a teacher with just a few years experience, it was a terrifying experience and one which very much formed my attitude to kids who tipped their chairs. And as I said I'd rather be a "real cow" than ever have had to go through it again. God knows what would happen now, then, thank goodness, parents were more understanding and didn't blame everything on teachers.