While we’re all here talking about schools, I thought I’d mention the other part of this conversation that we had while investigating this issue - namely the difference between the official definitions of isced:level and the actual usage when tagged on UK schools. As explained on Key:isced:level - OpenStreetMap Wiki and this document, year 7-9 studies are isced:level 2 and y10-11 (GCSE) studies are isced:level 3, together with y12-13 (A-levels). However, the tagging used on UK schools considers GCSEs part of isced:level 2. We can see this in the fact that, under the official definition, every secondary school should be tagged isced:level 2;3 for providing education from years 7-11, and that no schools would be tagged isced:level 2 (because no schools provide education for only y 7-9). However, there are 1581 schools in the UK tagged isced:level 2.
This was the rationale behind @ceirios wanting clarity on how to tag grades=, because according to the official isced levels a secondary school without a sixth form would be tagged the exact same as one with a sixth form, making the isced:level tag useless for differentiating between the two.
A similar discrepancy arises with Reception, which is officially classed as part of isced:level 0, meaning all primary schools should be tagged isced:level=0;1, but in practice this tag is only used for primary schools with a nursery.
I understand the rationale between using the system ‘incorrectly’, as it allows us to differentiate whether a school has a nursery or has a sixth form, but maybe it was wrong to do this and we should rely on some other, more UK-friendly tag to indicate these differences.