Clearly, it's possible to do much better than the status quo, E.g.:
"Squeak Etoys, Children & Learning", Alan Kay
> The projects developed in Squeak use a different and simpler kind of incremental mathematics that allows very young children to understand some of the key ideas in calculus. We have found that more than 90% of 5th graders not only understand “Galilean gravity” but are able to derive the mathematical “formulas” (actually 2nd order differential equations) using this alternative mathematics, and author a simulation that matches up very well with the experimental data.
http://www.vpri.org/pdf/rn2005001_learning.pdf
Or László Polgár
> László Polgár (born 11 May 1946) is a Hungarian chess teacher and educational psychologist. He is the father of the famous Polgár sisters: Zsuzsa, Zsófia, and Judit, whom he raised to be chess prodigies, with Judit and Zsuzsa becoming the best and second-best female chess players in the world, respectively.