Overcrowding in school may be a factor in a student achieving NCEA

Canterbury researchers claim extra time in the early years at school can make up to 40 per cent difference at level 3 NCEA .

Children born in the first half of the year get up to 6 months more time in early education at school.

Neuroscience educator Nathan Wallis says many schools move students before they're ready - to make space in new-entrant classes.