Good learners […] know how to ask meaningful questions; they are persistent in examining their own assumptions; they use definitions and metaphors as instruments for their thinking and are rarely trapped by their own language; they are apt to be cautious and precise in making generalizations, and they engage continually in verifying what they believe.
Neil Postman and Charles Weingartner. Teaching as a Subversive Activity. Penguin Education, 1969. Quoted in Diana Laurillard. Teaching as a Design Science. Routledge, 2012.