What we don’t know that sometimes won’t hurt us

Kevin Drum channels Brad DeLong to recall a Calvin and Hobbes sequence in which Calvin’s dad reassures him that it’s colder in the winter because the earth is farther from the sun then than in the summer. Kevin asks for a survey to find out how many people believe that.  As it happens, a small survey was performed a decade or so ago and it turns out that 21 out of 23 graduating Harvard seniors, alumni and faculty do. Ask your friends, it is to weep.  It’s the lede for an unforgettable investigation of why our science teaching doesn’t work, available here (just click on the VoD button in the lower right).

Our science teaching doesn’t work because we teach science as a sort of catechetical stream of truths that students memorize to repeat on exams, but trowel lightly over stuff they already know that is wrong. You can read all about it on the research page at the PhET project.  Because a lot of it makes no difference in daily life (most people can live just fine thinking the earth is flat), this crust of learning flakes off quickly.  Not understanding the seasons is one of the very striking examples of this, and another is the explanation, recited by people who have seen a paper airplane in action (flat wings) and an airplane flying upside down (at least in movies), that an airplane flies because its wings are rounded on top and flat on the bottom (plus some stuff with Bernoulli’s equation).  (Amazingly, even PhET has, among its wonderful teaching simulations,  the wrong model of aerodynamic lift!)

Unfortunately, a real model of lift involves some very hairy differential equations.  If you calculate the pressure difference between the top and bottom of a conventional wing from Bernoulli’s equation, and the implied velocity difference, you do not get the lift on a unit length of wing; you get a meaningless number. The simple model allows something that looks a lot like science (it has an actual quadratic equation!), but this teaching convenience requires students to build a wall between what they know to be true from real observation and what’s expected on the exam.

Very few people have occasion to intervene in aeronautic design or planetary motion, but there’s a lot more science, like heat transfer in and out of your house, that can hurt you if you don’t really get it, and still more, like climate science, that will hurt all of us if we go on voting in profound ignorance.  Teaching science like religion is a practice embedded both in the curriculum and the pedagogy, not to mention how easy it is to test without, like, having to find out whether any actual learning has occurred.