I agree on the needed flexibility part.
> the best system btw is montesori
I disagree on that. See a recent HN discussion on Montessori: https://news.ycombinator.com/item?id=45674002
tl;dr: it works for some kids, just like the current German system works for some (other) kids.
you may notice that i took an active part in that discussion.
tl;dr: montessori really does work for almost all kids, not just for some. the cases in the discussion where montessori didn't work don't provide any evidence that they actually received real montessori education as the name "montessori" is not protected.