Good historical works on medieval educational methods?

[davidjackson]

so how did they teach and train this skill?

A large stick and much hard work, I reckon.  
I think old Bill Ockham said it best: “No more things should be presumed to exist than are absolutely necessary.” In other words, if it isn't self-evident, or God didn't say it, best leave it alone and just use the tools you have.