Physicists Seek To Lose The Lecture As Teaching Tool : NPR
The lecture is one of the oldest forms of education there is.
“Before printing someone would read the books to everybody who would copy them down,” says Joe Redish, a physics professor at the University of Maryland.
But lecturing has never been an effective teaching technique and now that information is everywhere, some say it’s a waste of time. Indeed, physicists have the data to prove it.
When Eric Mazur began teaching physics at Harvard, he started out teaching the same way he had been taught.
“I sort of projected my own experience, my own vision of learning and teaching — which is what my instructors had done to me. So I lectured,” he says.
He loved to lecture. Mazur’s students apparently loved it, too. They gave him great evaluations and his classes were full.
“For a long while, I thought I was doing a really, really good job,” he says.
But then in 1990, he came across articles written by David Hestenes, a physicist at Arizona State. Hestenes got the idea for the series when a colleague came to him with a problem. The students in his introductory physics courses were not doing well: Semester after semester, the class average never got above about 40 percent.
“I noted that the reason for that was that his examination questions were mostly qualitative, requiring understanding of the concepts rather than just calculational, using formulas, which is what most of the instructors did,” Hestenes says.
Hestenes had a suspicion students were just memorizing the formulas and never really getting the concepts. So he and a colleague developed a test to look at students’ conceptual understanding of physics. It’s a test Maryland’s Redish has given his students many times.
Here’s a question from the test: “Two balls are the same size but one weighs twice as much as the other. The balls are dropped from the top of a two-story building at the same instant of time. The time it takes the ball to reach the ground will be…”
The possible answers include about half as long for the heavier ball, about half as long for the lighter ball, or the same time for both. This is a fundamental concept but even some people who’ve taken physics get this question wrong.
To get to the answer, Redish went to the second floor of the physics building. A group of his students was on the sidewalk below. When he reached the top, he dropped two balls from the roof.
The two balls reached the ground at the same time. Sir Isaac Newton was the first person who figured out why. He came up with a law of motion to explain how two balls of different weights, dropped from the same height, hit the ground simultaneously.
While most physics students can recite Newton’s second law of motion, Harvard’s Mazur says, the conceptual test developed by Hestenes showed that after an entire semester they understood only about 14 percent more about the fundamental concepts of physics. When Mazur read the results, he shook his head in disbelief. The test covered such basic material.
“I gave it to my students only to discover that they didn’t do much better,” he says.