Certain slow processes unfold so wonderfully that I can watch subtle changes for hours with no desire to speed them up: the emergence of an adult dragonfly from its larval exoskeleton, the way a stream carries sand as it flows…

Throughout my forty years of teaching, I’ve often ruminated on specific instances when I learned something from a teacher. What was it about that interaction out of thousands of classroom hours that fixed in my long-term memory? What did the…