[wahern]

c) Socratic method where an instructor guides inquiry using incisive questioning but never provides answers outright.

You'll always need "a)" for basic reading, writing, and arithmetic, and for providing basic facts and principles. "b)" doesn't even require a school as it's something kids should be doing, anyhow. It's also expensive, especially when you get to more abstract concepts, which is why this is a type of education typically only enjoyed by the privileged, both inside and outside school. And it can't accomplish the depth of understanding that "c)" can, nor cultivate more general analytical skills.

"c)" is the most important, but it also requires the most skilled teachers, especially in middle and high school. It could easily be applied more widely in elementary school, though.