If you're suggesting that a typical school day in England delivers enough or nearly enough hours of strong-enough sunlight then that seems hard to square with t

If you're suggesting that a typical school day in England delivers enough or nearly enough hours of strong-enough sunlight then that seems hard to square with the large increase in myopia right across the developed world, not just Asia (unless one rejects the strong-light hypothesis, of course). If strong light on its own isn't sufficient then of course adding artificial light to classrooms won't be sufficient; but in that case the Yangxi school experiment presumably won't be successful either.