The Bigger Ball Drops Faster — and Other Myths of Physics

Our minds are filled with folk science — and it gets in the way of real learning

Seasons are caused by the earth’s distance from the sun. Motors and other machines use up energy. A heavier ball falls faster than a lighter one. If these propositions sound right to you, that’s only natural — they’re examples of folk science, widely-shared but faulty assumptions about how the physical world works. The prevalence and the tenacity of such beliefs poses a dilemma for science educators and for anyone who would like to claim a worldview closer to Issac Newton’s than Conan the Barbarian’s: how do we get rid of notions that hold so much intuitive appeal? Learning researchers are investigating just where these folk ideas come from and developing surprising new ways to counter them.
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One thing is clear from the outset: traditional teaching methods don’t do much to uproot folk beliefs. Students in conventional classrooms listen to the correct explanation, read it in a textbook and may even produce it on an exam, but their bedrock assumptions remain untouched. In A Private Universe, a classic 1987 film produced by the Harvard-Smithsonian Center for Astrophysics, Harvard graduates are shown offering patently false explanations for common natural events. The problem with conventional science instruction, according to cognitive scientist Susan Carey, is that it assumes that its goal is to fill a gap in a student’s knowledge — when really the issue “is not what the student lacks, but what the student has, namely alternative conceptual frameworks for understanding the phenomena covered by the theories we are trying to teach.” In order to persuade students to embrace new and more accurate ideas about how the world operates, science teachers need to find out which “alternative conceptual frameworks” — myths — they already hew to. To that end, researchers have developed student surveys that can help instructors identify the beliefs their pupils have when they walk through the classroom door. These surveys show the same handful of misconceptions showing up again and again, espoused by strong students as well as weak ones.
Another promising approach is to directly confront individuals with the differences between their understanding and the correct one: to “offend the student’s intuition,” in the words of University of Wyoming astronomy professor Tim Slater. In a study to be published next month in the journal Learning and Instruction, scientists from the University of Pittsburgh asked one group of students to compare a diagram of their own inaccurate conception of the body’s circulatory system to an accurate drawing; a second group was required simply to explain the correct version. The students who engaged in a “confrontation” with the facts, the investigators reported, were more likely to acquire a valid mental model and a deeper understanding of the material. Researchers are now developing a variety of ways of presenting students with disconfirming evidence, such as live demonstrations, online videos, computer simulations, animated visualizations and interactive tutoring programs tailored to the student’s particular misconceptions.
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A third intriguing possibility is suggested by an experiment conducted by Laura-Ann Petitto and Kevin Dunbar of Dartmouth University. Two groups — one made up of advanced physics students, the other of students with very little knowledge of the subject — were shown a pair of films depicting two balls of apparently different masses falling from above and hitting the ground. The first film, which the authors called the Newtonian movie, showed the balls hitting the ground at the same time (as they would in reality.) The second clip, dubbed the naive movie, showed the larger and presumably heavier ball hitting the ground first. The students watched these films while having their brains scanned by an fMRI machine. The scans revealed that both groups recognized the naive scenario — but only the advanced students’ brains showed activation patterns that indicated an effort to suppress that knowledge. In other words, the difference between the two groups lay in their capacity to suppress inaccurate information.
This finding offers a clue as to why metacognitive skills like focus, attention and self-control are so key to learning. Sometimes, learning something new requires ignoring what we already know — and not just in science. It takes mental strength and flexibility, for example, to let go of the syntax of our native tongue and adopt instead the patterns of a foreign language or to set aside the attitudes of the present and imagine life from the perspective of historical figures. We may never get rid of our inner ignoramus, but we can train it to stay quiet.


TIME