Indeed it would, but it's probably really difficult to research this, as you need a large population, and there will be plenty of external factors acting on tho

Indeed it would, but it's probably really difficult to research this, as you need a large population, and there will be plenty of external factors acting on those populations. You'd ideally want to use students with the same (or similar) age, and similar ability levels. Where do you find a suitably large number of those from? Then you'd need to remove any external influences - the effect of a good or bad teacher, for example. That's not to say it can't be done, but is a much larger and more expensive piece of research.