FINDING THOSE TEACHABLE MOMENTS. Betsy's Page and Joanne Jacobs both link to a lament by Douglas Kern on the state of teaching in the engineering colleges. At both sites, the engineers have weighed in strongly suggesting that engineers might be born tinkerers, and the consequences of getting the Wrong Answer are sufficiently dire that the kinds of things teachers and professors might do to protect the fragile self-esteems of late adolescents (right -- name me a cohort more sure of itself than that cohort) would be somewhere between malpractice and manslaughter. Dilettantes need not apply.
All the same, some of the comments Mr Kern makes about the methods of teaching challenging things are spot on. If people are having trouble working a difficult problem (that might be "Sand falls onto a conical pile ...") simply working that problem, or a similar problem, or a variation on the problem, without laying out the concept first doesn't quite do the job. One must first get the apprentices grasping the proper Big Idea before expecting that they will be able to apply it.