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gwern comments on Guessing the Teacher's Password - Less Wrong

62 Post author: Eliezer_Yudkowsky 22 August 2007 03:40AM

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Comment author: gwern 12 July 2012 06:19:40PM 7 points [-]

In 1990, after seven years of teaching at Harvard, Eric Mazur, now Balkanski professor of physics and applied physics, was delivering clear, polished lectures and demonstrations and getting high student evaluations for his introductory Physics 11 course, populated mainly by premed and engineering students who were successfully solving complicated problems. Then he discovered that his success as a teacher “was a complete illusion, a house of cards.”

The epiphany came via an article in the American Journal of Physics by Arizona State professor David Hestenes. He had devised a very simple test, couched in everyday language, to check students’ understanding of one of the most fundamental concepts of physics—force—and had administered it to thousands of undergraduates in the southwestern United States. Astonishingly, the test showed that their introductory courses had taught them “next to nothing,” says Mazur: “After a semester of physics, they still held the same misconceptions as they had at the beginning of the term.”

The students had improved at handling equations and formulas, he explains, but when it came to understanding “what the real meanings of these things are, they basically reverted to Aristotelian logic—thousands of years back.” For example, they could recite Newton’s Third Law and apply it to numerical problems, but when asked about a real-world event like a collision between a heavy truck and a light car, many firmly declared that the heavy truck exerts a larger force. (Actually, an object’s weight is irrelevant to the force exerted.)

Mazur tried the test on his own students. Right at the start, a warning flag went up when one student raised her hand and asked, “How should I answer these questions—according to what you taught me, or how I usually think about these things?” To Mazur’s consternation, the simple test of conceptual understanding showed that his students had not grasped the basic ideas of his physics course: two-thirds of them were modern Aristotelians. “The students did well on textbook-style problems,” he explains. “They had a bag of tricks, formulas to apply. But that was solving problems by rote. They floundered on the simple word problems, which demanded a real understanding of the concepts behind the formulas.”


Comment author: CAE_Jones 30 January 2013 03:55:55AM 0 points [-]

This reminds me of an exchange from when I was in highschool physics, talking with someone a year ahead of me who was a freshman in college physics.

I've tried looking for the original conversation, but we apparently talked about Batman, asteroids and boats too much for Google to find it.

Basically, I posted a problem from my Physics homework in which we had to determine what would happen if Batman jumped off a bridge into a passing boat, in which a criminal was making an escape (or committing a crime, or some such thing).

He complained that the only problems he got were random asteroid collisions in the middle of Nowhere, Space.

There was another that was descriptive rather than involving solving an equation, asking to explain what was wrong in the situation where Superman, hovering in an alley, reaches down to grab a fleeing criminal, without moving in any other way. (Conservation of momentum, and all that). He attended a certain prestigeous engineering university in the American Midwest, and I was at my state's Math and Science school (Juniors/seniors, science fair was a big deal taking up a year and then some, and I didn't have to go through a horrible chain of time-consuming prerequesits to get into most of the classes I wanted to take).

We both bailed on math and physics around the same time, after Calculus 2. And lab reports in college physics proved a huge obstacle (if the overwhelming ugh fields around academic writing weren't enough, the fact that we were mostly just letting a cart roll down a slope, and writing about it in the context of the phenomenon of the week made my only interest in pointing out sources of error rather than treating it as an actual experiment).

I then proceeded to sit in a building for the next five years and fail roughly one class every other semester for three of those years, and still don't have the piece of paper saying I can speak French. Looking for the above-mentioned conversation did bring up posts where I could actually speak math, though, making me wonder how things would have gone had I found Overcoming Bias / LessWrong in 2007 or 2008. (Perhaps I would have been less prone to go off on wild tangents complaining about my life? Hmm...)

Comment author: Jiro 28 December 2015 01:31:38AM 0 points [-]

(Response to old post.)

If you're postulating anything like most people's ideas of Superman, you're already saying "ignore conservation of momentum", because inherent in the concept is that he flies around in arbitrary ways without having to push on anything. In other words, by the way you phrased the problem, you just asked the student to ignore the very thing you're asking the problem about. This won't turn out well.