As someone who advises my employer's schools, I agree with Zyggy's comments about RIDDOR and schools. Though RIDDOR is supposed to be a comprehensive piece of legislation, I suspect that little thought was given to the education sector when RIDDOR was being framed. For example the front page of notification form F2508 does not include any clear category under Part C for indicating when appropriate that the report concerns a pupil/student. The nearest category available is "member of the public".
Mootoppers mentions being expected to report incidents relating to curriculum sports. This almost certainly stems from advice in HSE's Education Information Sheet No 1 (rev1) "Incident-reporting in schools (accidents, diseases and dangerous occurrences)" to be found at
http://www.hse.gov.uk/pubns/edis1.pdfUnder the heading "What about sports activities?" the sheet advises that "accidents and incidents that happen in relation to curriculum sports activities and result in pupils being killed or taken to hospital for treatment are reportable." However, this brief paragraph does not accord with what is required by law, i.e. RIDDOR.
Therefore, if a pupil is taken to hospital with an injury which occurred during PE or curriculum sports, it is NOT reportable unless an identifiable deficiency was involved, e.g. a measurable hole in a playing field surface or the use of an slippery ice-covered hard surface. Though the same reasoning could be applied to a pupil death during school sport/PE activities, it would be prudent nevertheless to inform HSE. This would give HSE the opportunity to work alongside the police who will inevitably have prompt involvement - as is the case for all unexpected deaths irrespective of where and how they occur.
Like Zyggy and DP I am firmly against "report if in doubt", for the reasons they cite. Also reporting only if necessary saves employers and HSE from spending/wasting valuable time and effort on unnecessary information.
It might help to mention that some years ago I was contacted by HSE and asked why no RIDDOR report had been made regarding an accident at one of my employer's primary schools in which a pupil had broken an arm. He had fallen off a low level balance trail comprising tyres which were 'semi-submerged' in a safety surface. I investigated and decided that no deficiencies were involved. The tyres (installed as new, not old worn ones) had reasonable grippy texture surfaces, and continuous adult supervision was not needed. Furthermore, pupils were regularly reminded in assemblies, etc to avoid running, crowding and pushing on the trail. The pupil had fallen off when pushed by a friend - nobody else on the trail - and had the misfortune to land awkwardly. One of his parents complained to HSE that the trail was dangerous, apparently to help pursue a claim for compensation. The mere receipt of a complaint by HSE seemed to underpin its insistence on receiving a RIDDOR notification about the injury.
Eventually HSE conceded that no notification was needed and that the trail - of the sort installed at various primary schools throughout the UK - was reasonably safe! Lesson: investigate, make and record your conclusion/s and stand by them.
Also, if feasible, for peace of mind - especially with regard to complex/contentious cases - it's handy to get a second opinion from one or two colleagues. People in other professions such as medicine seek second opinions where appropriate, so why should OS&H practitioners be any different?